[LSC] Replace base::string16 with std::u16string in //[a-e]*

This change replaces base::string16 with std::u16string in //[a-e]*.

Reproduction steps:
$ git grep -lw 'base::string16' [a-e]* | \
      xargs sed -i 's/\bbase::string16\b/std::u16string/g'
$ git cl format

Bug: 1184339
Change-Id: I7930c2c3ae510b6d2232cc1b3a927ad90515ffe9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2752407
Commit-Queue: Jan Wilken Dörrie <jdoerrie@chromium.org>
Owners-Override: Jan Wilken Dörrie <jdoerrie@chromium.org>
Reviewed-by: Peter Kasting <pkasting@chromium.org>
Cr-Commit-Position: refs/heads/master@{#862191}

android_webview/browser/aw_autofill_client.cc

@@ -138,13 +138,13 @@ void AwAutofillClient::OnUnmaskVerificationResult(PaymentsRpcResult result) {
 }
 
 void AwAutofillClient::ConfirmAccountNameFixFlow(
-    base::OnceCallback<void(const base::string16&)> callback) {
+    base::OnceCallback<void(const std::u16string&)> callback) {
   NOTIMPLEMENTED();
 }
 
 void AwAutofillClient::ConfirmExpirationDateFixFlow(
     const autofill::CreditCard& card,
-    base::OnceCallback<void(const base::string16&, const base::string16&)>
+    base::OnceCallback<void(const std::u16string&, const std::u16string&)>
         callback) {
   NOTIMPLEMENTED();
 }
@@ -205,8 +205,8 @@ void AwAutofillClient::ShowAutofillPopup(
 }
 
 void AwAutofillClient::UpdateAutofillPopupDataListValues(
-    const std::vector<base::string16>& values,
-    const std::vector<base::string16>& labels) {
+    const std::vector<std::u16string>& values,
+    const std::vector<std::u16string>& labels) {
   // Leaving as an empty method since updating autofill popup window
   // dynamically does not seem to be a useful feature for android webview.
   // See crrev.com/18102002 if need to implement.
@@ -257,8 +257,8 @@ void AwAutofillClient::PropagateAutofillPredictions(
     const std::vector<autofill::FormStructure*>& forms) {}
 
 void AwAutofillClient::DidFillOrPreviewField(
-    const base::string16& autofilled_value,
-    const base::string16& profile_full_name) {}
+    const std::u16string& autofilled_value,
+    const std::u16string& profile_full_name) {}
 
 bool AwAutofillClient::IsContextSecure() const {
   content::SSLStatus ssl_status;

android_webview/browser/aw_autofill_client.h

@@ -84,10 +84,10 @@ class AwAutofillClient : public autofill::AutofillClient,
       base::WeakPtr<autofill::CardUnmaskDelegate> delegate) override;
   void OnUnmaskVerificationResult(PaymentsRpcResult result) override;
   void ConfirmAccountNameFixFlow(
-      base::OnceCallback<void(const base::string16&)> callback) override;
+      base::OnceCallback<void(const std::u16string&)> callback) override;
   void ConfirmExpirationDateFixFlow(
       const autofill::CreditCard& card,
-      base::OnceCallback<void(const base::string16&, const base::string16&)>
+      base::OnceCallback<void(const std::u16string&, const std::u16string&)>
           callback) override;
   void ConfirmSaveCreditCardLocally(
       const autofill::CreditCard& card,
@@ -110,8 +110,8 @@ class AwAutofillClient : public autofill::AutofillClient,
       const autofill::AutofillClient::PopupOpenArgs& open_args,
       base::WeakPtr<autofill::AutofillPopupDelegate> delegate) override;
   void UpdateAutofillPopupDataListValues(
-      const std::vector<base::string16>& values,
-      const std::vector<base::string16>& labels) override;
+      const std::vector<std::u16string>& values,
+      const std::vector<std::u16string>& labels) override;
   base::span<const autofill::Suggestion> GetPopupSuggestions() const override;
   void PinPopupView() override;
   autofill::AutofillClient::PopupOpenArgs GetReopenPopupArgs() const override;
@@ -122,8 +122,8 @@ class AwAutofillClient : public autofill::AutofillClient,
   void PropagateAutofillPredictions(
       content::RenderFrameHost* rfh,
       const std::vector<autofill::FormStructure*>& forms) override;
-  void DidFillOrPreviewField(const base::string16& autofilled_value,
-                             const base::string16& profile_full_name) override;
+  void DidFillOrPreviewField(const std::u16string& autofilled_value,
+                             const std::u16string& profile_full_name) override;
   bool IsContextSecure() const override;
   bool ShouldShowSigninPromo() override;
   bool AreServerCardsSupported() const override;

android_webview/browser/aw_content_browser_client.cc

@@ -762,7 +762,7 @@ bool AwContentBrowserClient::ShouldOverrideUrlLoading(
   if (client_bridge == nullptr)
     return true;
 
-  base::string16 url = base::UTF8ToUTF16(gurl.possibly_invalid_spec());
+  std::u16string url = base::UTF8ToUTF16(gurl.possibly_invalid_spec());
   return client_bridge->ShouldOverrideUrlLoading(
       url, has_user_gesture, is_redirect, is_main_frame, ignore_navigation);
 }

android_webview/browser/aw_contents.cc

@@ -535,12 +535,12 @@ void AwContents::AddVisitedLinks(
     const JavaParamRef<jobject>& obj,
     const JavaParamRef<jobjectArray>& jvisited_links) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
-  std::vector<base::string16> visited_link_strings;
+  std::vector<std::u16string> visited_link_strings;
   base::android::AppendJavaStringArrayToStringVector(env, jvisited_links,
                                                      &visited_link_strings);
 
   std::vector<GURL> visited_link_gurls;
-  std::vector<base::string16>::const_iterator itr;
+  std::vector<std::u16string>::const_iterator itr;
   for (itr = visited_link_strings.begin(); itr != visited_link_strings.end();
        ++itr) {
     visited_link_gurls.push_back(GURL(*itr));
@@ -1381,12 +1381,12 @@ base::android::ScopedJavaLocalRef<jstring> AwContents::AddWebMessageListener(
     const base::android::JavaParamRef<jobject>& listener,
     const base::android::JavaParamRef<jstring>& js_object_name,
     const base::android::JavaParamRef<jobjectArray>& allowed_origin_rules) {
-  base::string16 native_js_object_name =
+  std::u16string native_js_object_name =
       base::android::ConvertJavaStringToUTF16(env, js_object_name);
   std::vector<std::string> native_allowed_origin_rule_strings;
   AppendJavaStringArrayToStringVector(env, allowed_origin_rules,
                                       &native_allowed_origin_rule_strings);
-  const base::string16 error_message =
+  const std::u16string error_message =
       GetJsCommunicationHost()->AddWebMessageHostFactory(
           std::make_unique<AwWebMessageHostFactory>(listener),
           native_js_object_name, native_allowed_origin_rule_strings);

android_webview/browser/aw_contents_client_bridge.cc

@@ -293,15 +293,15 @@ void AwContentsClientBridge::ProvideClientCertificateResponse(
 void AwContentsClientBridge::RunJavaScriptDialog(
     content::JavaScriptDialogType dialog_type,
     const GURL& origin_url,
-    const base::string16& message_text,
-    const base::string16& default_prompt_text,
+    const std::u16string& message_text,
+    const std::u16string& default_prompt_text,
     content::JavaScriptDialogManager::DialogClosedCallback callback) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   JNIEnv* env = AttachCurrentThread();
 
   ScopedJavaLocalRef<jobject> obj = java_ref_.get(env);
   if (!obj) {
-    std::move(callback).Run(false, base::string16());
+    std::move(callback).Run(false, std::u16string());
     return;
   }
 
@@ -347,11 +347,11 @@ void AwContentsClientBridge::RunBeforeUnloadDialog(
 
   ScopedJavaLocalRef<jobject> obj = java_ref_.get(env);
   if (!obj) {
-    std::move(callback).Run(false, base::string16());
+    std::move(callback).Run(false, std::u16string());
     return;
   }
 
-  const base::string16 message_text =
+  const std::u16string message_text =
       l10n_util::GetStringUTF16(IDS_BEFOREUNLOAD_MESSAGEBOX_MESSAGE);
 
   int callback_id = pending_js_dialog_callbacks_.Add(
@@ -367,7 +367,7 @@ void AwContentsClientBridge::RunBeforeUnloadDialog(
                                                    callback_id);
 }
 
-bool AwContentsClientBridge::ShouldOverrideUrlLoading(const base::string16& url,
+bool AwContentsClientBridge::ShouldOverrideUrlLoading(const std::u16string& url,
                                                       bool has_user_gesture,
                                                       bool is_redirect,
                                                       bool is_main_frame,
@@ -553,7 +553,7 @@ void AwContentsClientBridge::ConfirmJsResult(JNIEnv* env,
     LOG(WARNING) << "Unexpected JS dialog confirm. " << id;
     return;
   }
-  base::string16 prompt_text;
+  std::u16string prompt_text;
   if (prompt) {
     prompt_text = ConvertJavaStringToUTF16(env, prompt);
   }
@@ -588,7 +588,7 @@ void AwContentsClientBridge::CancelJsResult(JNIEnv*,
     LOG(WARNING) << "Unexpected JS dialog cancel. " << id;
     return;
   }
-  std::move(*callback).Run(false, base::string16());
+  std::move(*callback).Run(false, std::u16string());
   pending_js_dialog_callbacks_.Remove(id);
 }
 

android_webview/browser/aw_contents_client_bridge.h

@@ -91,13 +91,13 @@ class AwContentsClientBridge {
   void RunJavaScriptDialog(
       content::JavaScriptDialogType dialog_type,
       const GURL& origin_url,
-      const base::string16& message_text,
-      const base::string16& default_prompt_text,
+      const std::u16string& message_text,
+      const std::u16string& default_prompt_text,
       content::JavaScriptDialogManager::DialogClosedCallback callback);
   void RunBeforeUnloadDialog(
       const GURL& origin_url,
       content::JavaScriptDialogManager::DialogClosedCallback callback);
-  bool ShouldOverrideUrlLoading(const base::string16& url,
+  bool ShouldOverrideUrlLoading(const std::u16string& url,
                                 bool has_user_gesture,
                                 bool is_redirect,
                                 bool is_main_frame,

android_webview/browser/aw_javascript_dialog_manager.cc

@@ -21,14 +21,14 @@ void AwJavaScriptDialogManager::RunJavaScriptDialog(
     content::WebContents* web_contents,
     content::RenderFrameHost* render_frame_host,
     content::JavaScriptDialogType dialog_type,
-    const base::string16& message_text,
-    const base::string16& default_prompt_text,
+    const std::u16string& message_text,
+    const std::u16string& default_prompt_text,
     DialogClosedCallback callback,
     bool* did_suppress_message) {
   AwContentsClientBridge* bridge =
       AwContentsClientBridge::FromWebContents(web_contents);
   if (!bridge) {
-    std::move(callback).Run(false, base::string16());
+    std::move(callback).Run(false, std::u16string());
     return;
   }
 
@@ -45,7 +45,7 @@ void AwJavaScriptDialogManager::RunBeforeUnloadDialog(
   AwContentsClientBridge* bridge =
       AwContentsClientBridge::FromWebContents(web_contents);
   if (!bridge) {
-    std::move(callback).Run(false, base::string16());
+    std::move(callback).Run(false, std::u16string());
     return;
   }
 

android_webview/browser/aw_javascript_dialog_manager.h

@@ -19,8 +19,8 @@ class AwJavaScriptDialogManager : public content::JavaScriptDialogManager {
   void RunJavaScriptDialog(content::WebContents* web_contents,
                            content::RenderFrameHost* render_frame_host,
                            content::JavaScriptDialogType dialog_type,
-                           const base::string16& message_text,
-                           const base::string16& default_prompt_text,
+                           const std::u16string& message_text,
+                           const std::u16string& default_prompt_text,
                            DialogClosedCallback callback,
                            bool* did_suppress_message) override;
   void RunBeforeUnloadDialog(content::WebContents* web_contents,

android_webview/browser/aw_pac_processor.cc

@@ -262,9 +262,9 @@ class Bindings : public proxy_resolver::ProxyResolverV8Tracing::Bindings {
  public:
   Bindings(HostResolver* host_resolver) : host_resolver_(host_resolver) {}
 
-  void Alert(const base::string16& message) override {}
+  void Alert(const std::u16string& message) override {}
 
-  void OnError(int line_number, const base::string16& message) override {}
+  void OnError(int line_number, const std::u16string& message) override {}
 
   proxy_resolver::ProxyHostResolver* GetHostResolver() override {
     return host_resolver_;

android_webview/browser/aw_quota_manager_bridge.cc

@@ -207,14 +207,14 @@ void AwQuotaManagerBridge::DeleteAllDataOnUiThread() {
 void AwQuotaManagerBridge::DeleteOrigin(JNIEnv* env,
                                         const JavaParamRef<jobject>& object,
                                         const JavaParamRef<jstring>& origin) {
-  base::string16 origin_string(
+  std::u16string origin_string(
       base::android::ConvertJavaStringToUTF16(env, origin));
   RunOnUIThread(base::BindOnce(&AwQuotaManagerBridge::DeleteOriginOnUiThread,
                                this, origin_string));
 }
 
 void AwQuotaManagerBridge::DeleteOriginOnUiThread(
-    const base::string16& origin) {
+    const std::u16string& origin) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   StoragePartition* storage_partition = GetStoragePartition();
   storage_partition->ClearDataForOrigin(
@@ -285,7 +285,7 @@ void AwQuotaManagerBridge::GetUsageAndQuotaForOrigin(
     const JavaParamRef<jstring>& origin,
     jint callback_id,
     bool is_quota) {
-  base::string16 origin_string(
+  std::u16string origin_string(
       base::android::ConvertJavaStringToUTF16(env, origin));
   RunOnUIThread(
       base::BindOnce(&AwQuotaManagerBridge::GetUsageAndQuotaForOriginOnUiThread,
@@ -293,7 +293,7 @@ void AwQuotaManagerBridge::GetUsageAndQuotaForOrigin(
 }
 
 void AwQuotaManagerBridge::GetUsageAndQuotaForOriginOnUiThread(
-    const base::string16& origin,
+    const std::u16string& origin,
     jint callback_id,
     bool is_quota) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);

android_webview/browser/aw_quota_manager_bridge.h

@@ -69,9 +69,9 @@ class AwQuotaManagerBridge
   storage::QuotaManager* GetQuotaManager() const;
 
   void DeleteAllDataOnUiThread();
-  void DeleteOriginOnUiThread(const base::string16& origin);
+  void DeleteOriginOnUiThread(const std::u16string& origin);
   void GetOriginsOnUiThread(jint callback_id);
-  void GetUsageAndQuotaForOriginOnUiThread(const base::string16& origin,
+  void GetUsageAndQuotaForOriginOnUiThread(const std::u16string& origin,
                                            jint callback_id,
                                            bool is_quota);
 

android_webview/browser/aw_web_contents_delegate.cc

@@ -338,7 +338,7 @@ static void JNI_AwWebContentsDelegate_FilesSelectedInChooser(
   }
 
   std::vector<std::string> file_path_str;
-  std::vector<base::string16> display_name_str;
+  std::vector<std::u16string> display_name_str;
   // Note file_paths maybe NULL, but this will just yield a zero-length vector.
   base::android::AppendJavaStringArrayToStringVector(env, file_paths,
                                                      &file_path_str);

android_webview/browser/find_helper.cc

@@ -31,7 +31,7 @@ void FindHelper::SetListener(Listener* listener) {
   listener_ = listener;
 }
 
-void FindHelper::FindAllAsync(const base::string16& search_string) {
+void FindHelper::FindAllAsync(const std::u16string& search_string) {
   // Stop any ongoing asynchronous request.
   web_contents()->StopFinding(content::STOP_FIND_ACTION_KEEP_SELECTION);
 
@@ -87,7 +87,7 @@ void FindHelper::ClearMatches() {
   last_active_ordinal_ = -1;
 }
 
-bool FindHelper::MaybeHandleEmptySearch(const base::string16& search_string) {
+bool FindHelper::MaybeHandleEmptySearch(const std::u16string& search_string) {
   if (!search_string.empty())
     return false;
 
@@ -96,7 +96,7 @@ bool FindHelper::MaybeHandleEmptySearch(const base::string16& search_string) {
   return true;
 }
 
-void FindHelper::StartNewSession(const base::string16& search_string) {
+void FindHelper::StartNewSession(const std::u16string& search_string) {
   current_request_id_ = find_request_id_counter_++;
   current_session_id_ = current_request_id_;
   last_search_string_ = search_string;

android_webview/browser/find_helper.h

@@ -32,7 +32,7 @@ class FindHelper : public content::WebContentsObserver {
   void SetListener(Listener* listener);
 
   // Asynchronous API.
-  void FindAllAsync(const base::string16& search_string);
+  void FindAllAsync(const std::u16string& search_string);
   void HandleFindReply(int request_id,
                        int match_count,
                        int active_ordinal,
@@ -43,8 +43,8 @@ class FindHelper : public content::WebContentsObserver {
   void ClearMatches();
 
  private:
-  void StartNewSession(const base::string16& search_string);
-  bool MaybeHandleEmptySearch(const base::string16& search_string);
+  void StartNewSession(const std::u16string& search_string);
+  bool MaybeHandleEmptySearch(const std::u16string& search_string);
   void NotifyResults(int active_ordinal, int match_count, bool finished);
 
   // Listener results are reported to.
@@ -63,7 +63,7 @@ class FindHelper : public content::WebContentsObserver {
   int current_session_id_;
 
   // Required by FindNext and the incremental find replies.
-  base::string16 last_search_string_;
+  std::u16string last_search_string_;
   int last_match_count_;
   int last_active_ordinal_;
 

android_webview/browser/renderer_host/aw_render_view_host_ext.cc

@@ -26,7 +26,7 @@ namespace {
 
 void ShouldOverrideUrlLoadingOnUI(
     content::WebContents* web_contents,
-    const base::string16& url,
+    const std::u16string& url,
     bool has_user_gesture,
     bool is_redirect,
     bool is_main_frame,
@@ -206,7 +206,7 @@ void AwRenderViewHostExt::ContentsSizeChanged(const gfx::Size& contents_size) {
 }
 
 void AwRenderViewHostExt::ShouldOverrideUrlLoading(
-    const base::string16& url,
+    const std::u16string& url,
     bool has_user_gesture,
     bool is_redirect,
     bool is_main_frame,

android_webview/browser/renderer_host/aw_render_view_host_ext.h

@@ -90,7 +90,7 @@ class AwRenderViewHostExt : public content::WebContentsObserver,
       android_webview::mojom::HitTestDataPtr hit_test_data) override;
   void ContentsSizeChanged(const gfx::Size& contents_size) override;
   void ShouldOverrideUrlLoading(
-      const base::string16& url,
+      const std::u16string& url,
       bool has_user_gesture,
       bool is_redirect,
       bool is_main_frame,

android_webview/browser/state_serializer.cc

@@ -233,7 +233,7 @@ bool RestoreNavigationEntryFromPickle(uint32_t state_version,
   }
 
   {
-    base::string16 title;
+    std::u16string title;
     if (!iterator->ReadString16(&title))
       return false;
     entry->SetTitle(title);

android_webview/browser/state_serializer_unittest.cc

@@ -33,7 +33,7 @@ std::unique_ptr<content::NavigationEntry> CreateNavigationEntry() {
   content::Referrer referrer;
   referrer.url = GURL("http://referrer_url");
   referrer.policy = network::mojom::ReferrerPolicy::kOrigin;
-  const base::string16 title(base::UTF8ToUTF16("title"));
+  const std::u16string title(base::UTF8ToUTF16("title"));
   const bool has_post_data = true;
   const GURL original_request_url("http://original_request_url");
   const GURL base_url_for_data_url("http://base_url");
@@ -182,7 +182,7 @@ TEST_F(AndroidWebViewStateSerializerTest,
   GURL virtual_url("https://example.com/virtual_url");
   content::Referrer referrer(GURL("https://example.com/referrer"),
                              network::mojom::ReferrerPolicy::kDefault);
-  base::string16 title = base::UTF8ToUTF16("title");
+  std::u16string title = base::UTF8ToUTF16("title");
   std::string empty_encoded_page_state = "";
   bool has_post_data = false;
   GURL original_request_url("https://example.com/original");

android_webview/common/aw_content_client.cc

@@ -36,7 +36,7 @@ void AwContentClient::AddAdditionalSchemes(Schemes* schemes) {
   schemes->allow_non_standard_schemes_in_origins = true;
 }
 
-base::string16 AwContentClient::GetLocalizedString(int message_id) {
+std::u16string AwContentClient::GetLocalizedString(int message_id) {
   // TODO(boliu): Used only by WebKit, so only bundle those resources for
   // Android WebView.
   return l10n_util::GetStringUTF16(message_id);

android_webview/common/aw_content_client.h

@@ -26,7 +26,7 @@ class AwContentClient : public content::ContentClient {
   ~AwContentClient() override;
   // ContentClient implementation.
   void AddAdditionalSchemes(Schemes* schemes) override;
-  base::string16 GetLocalizedString(int message_id) override;
+  std::u16string GetLocalizedString(int message_id) override;
   base::StringPiece GetDataResource(int resource_id,
                                     ui::ScaleFactor scale_factor) override;
   base::RefCountedMemory* GetDataResourceBytes(int resource_id) override;

android_webview/renderer/aw_content_renderer_client.cc

@@ -136,7 +136,7 @@ bool AwContentRendererClient::HandleNavigation(
   }
 
   bool ignore_navigation = false;
-  base::string16 url = request.Url().GetString().Utf16();
+  std::u16string url = request.Url().GetString().Utf16();
   bool has_user_gesture = request.HasUserGesture();
 
   mojo::AssociatedRemote<mojom::FrameHost> frame_host_remote;

android_webview/renderer/aw_render_frame_ext.cc

@@ -41,12 +41,12 @@ const char kEmailPrefix[] = "mailto:";
 const char kPhoneNumberPrefix[] = "tel:";
 
 GURL GetAbsoluteUrl(const blink::WebNode& node,
-                    const base::string16& url_fragment) {
+                    const std::u16string& url_fragment) {
   return GURL(node.GetDocument().CompleteURL(
       blink::WebString::FromUTF16(url_fragment)));
 }
 
-base::string16 GetHref(const blink::WebElement& element) {
+std::u16string GetHref(const blink::WebElement& element) {
   // Get the actual 'href' attribute, which might relative if valid or can
   // possibly contain garbage otherwise, so not using absoluteLinkURL here.
   return element.GetAttribute("href").Utf16();

apps/load_and_launch_browsertest.cc

@@ -216,7 +216,7 @@ IN_PROC_BROWSER_TEST_F(LoadAndLaunchPlatformAppBrowserTest,
 #endif
 IN_PROC_BROWSER_TEST_F(LoadAndLaunchExtensionBrowserTest,
                        MAYBE_LoadAndLaunchExtension) {
-  const std::vector<base::string16>* errors =
+  const std::vector<std::u16string>* errors =
       extensions::LoadErrorReporter::GetInstance()->GetErrors();
 
 #if BUILDFLAG(GOOGLE_CHROME_BRANDING)
@@ -225,7 +225,7 @@ IN_PROC_BROWSER_TEST_F(LoadAndLaunchExtensionBrowserTest,
 #else
   // Expect |extension_instead_of_app_error|.
   EXPECT_EQ(1u, errors->size());
-  EXPECT_NE(base::string16::npos,
+  EXPECT_NE(std::u16string::npos,
             errors->at(0).find(base::ASCIIToUTF16(
                 "App loading flags cannot be used to load extensions")));
 #endif

ash/accelerators/accelerator_controller_impl.cc

@@ -188,8 +188,8 @@ void RecordTabletVolumeAdjustTypeHistogram(TabletModeVolumeAdjustType type) {
 
 // Ensures that there are no word breaks at the "+"s in the shortcut texts such
 // as "Ctrl+Shift+Space".
-void EnsureNoWordBreaks(base::string16* shortcut_text) {
-  std::vector<base::string16> keys =
+void EnsureNoWordBreaks(std::u16string* shortcut_text) {
+  std::vector<std::u16string> keys =
       base::SplitString(*shortcut_text, base::ASCIIToUTF16("+"),
                         base::TRIM_WHITESPACE, base::SPLIT_WANT_ALL);
 
@@ -198,7 +198,7 @@ void EnsureNoWordBreaks(base::string16* shortcut_text) {
 
   // The plus sign surrounded by the word joiner to guarantee an non-breaking
   // shortcut.
-  const base::string16 non_breaking_plus =
+  const std::u16string non_breaking_plus =
       base::UTF8ToUTF16("\xe2\x81\xa0+\xe2\x81\xa0");
   shortcut_text->clear();
   for (size_t i = 0; i < keys.size() - 1; ++i) {
@@ -211,11 +211,11 @@ void EnsureNoWordBreaks(base::string16* shortcut_text) {
 
 // Gets the notification message after it formats it in such a way that there
 // are no line breaks in the middle of the shortcut texts.
-base::string16 GetNotificationText(int message_id,
+std::u16string GetNotificationText(int message_id,
                                    int old_shortcut_id,
                                    int new_shortcut_id) {
-  base::string16 old_shortcut = l10n_util::GetStringUTF16(old_shortcut_id);
-  base::string16 new_shortcut = l10n_util::GetStringUTF16(new_shortcut_id);
+  std::u16string old_shortcut = l10n_util::GetStringUTF16(old_shortcut_id);
+  std::u16string new_shortcut = l10n_util::GetStringUTF16(new_shortcut_id);
   EnsureNoWordBreaks(&old_shortcut);
   EnsureNoWordBreaks(&new_shortcut);
 
@@ -227,7 +227,7 @@ void ShowDeprecatedAcceleratorNotification(const char* const notification_id,
                                            int message_id,
                                            int old_shortcut_id,
                                            int new_shortcut_id) {
-  const base::string16 message =
+  const std::u16string message =
       GetNotificationText(message_id, old_shortcut_id, new_shortcut_id);
   auto delegate =
       base::MakeRefCounted<message_center::HandleNotificationClickDelegate>(
@@ -239,7 +239,7 @@ void ShowDeprecatedAcceleratorNotification(const char* const notification_id,
   std::unique_ptr<Notification> notification = ash::CreateSystemNotification(
       message_center::NOTIFICATION_TYPE_SIMPLE, notification_id,
       l10n_util::GetStringUTF16(IDS_DEPRECATED_SHORTCUT_TITLE), message,
-      base::string16(), GURL(),
+      std::u16string(), GURL(),
       message_center::NotifierId(message_center::NotifierType::SYSTEM_COMPONENT,
                                  kNotifierAccelerator),
       message_center::RichNotificationData(), std::move(delegate),
@@ -248,7 +248,7 @@ void ShowDeprecatedAcceleratorNotification(const char* const notification_id,
       std::move(notification));
 }
 
-void ShowToast(std::string id, const base::string16& text) {
+void ShowToast(std::string id, const std::u16string& text) {
   ToastData toast(id, text, kToastDurationMs, base::nullopt,
                   /*visible_on_lock_screen=*/true);
   Shell::Get()->toast_manager()->Show(toast);
@@ -1255,13 +1255,13 @@ bool CanHandleToggleOverview() {
   return true;
 }
 
-void CreateAndShowStickyNotification(const base::string16& title,
-                                     const base::string16& message,
+void CreateAndShowStickyNotification(const std::u16string& title,
+                                     const std::u16string& message,
                                      const std::string& notification_id,
                                      const gfx::VectorIcon& icon) {
   std::unique_ptr<Notification> notification = ash::CreateSystemNotification(
       message_center::NOTIFICATION_TYPE_SIMPLE, notification_id, title, message,
-      base::string16() /* display source */, GURL(),
+      std::u16string() /* display source */, GURL(),
       message_center::NotifierId(message_center::NotifierType::SYSTEM_COMPONENT,
                                  kNotifierAccelerator),
       message_center::RichNotificationData(), nullptr, icon,
@@ -1285,7 +1285,7 @@ void NotifyAccessibilityFeatureDisabledByAdmin(
     int feature_name_id,
     bool feature_state,
     const std::string& notification_id) {
-  const base::string16 organization_manager =
+  const std::u16string organization_manager =
       base::UTF8ToUTF16(Shell::Get()
                             ->system_tray_model()
                             ->enterprise_domain()

ash/accelerators/exit_warning_handler.cc

@@ -79,8 +79,8 @@ class ExitWarningWidgetDelegateView : public views::WidgetDelegateView {
   }
 
  private:
-  base::string16 text_;
-  base::string16 accessible_name_;
+  std::u16string text_;
+  std::u16string accessible_name_;
   int text_width_;
 
   DISALLOW_COPY_AND_ASSIGN(ExitWarningWidgetDelegateView);

ash/accessibility/accessibility_controller_impl.cc

@@ -325,8 +325,8 @@ void ShowAccessibilityNotification(A11yNotificationType type) {
   if (type == A11yNotificationType::kNone)
     return;
 
-  base::string16 text;
-  base::string16 title;
+  std::u16string text;
+  std::u16string title;
   if (type == A11yNotificationType::kBrailleDisplayConnected) {
     text = l10n_util::GetStringUTF16(
         IDS_ASH_STATUS_TRAY_BRAILLE_DISPLAY_CONNECTED);
@@ -350,7 +350,7 @@ void ShowAccessibilityNotification(A11yNotificationType type) {
   std::unique_ptr<message_center::Notification> notification =
       ash::CreateSystemNotification(
           message_center::NOTIFICATION_TYPE_SIMPLE, kNotificationId, title,
-          text, base::string16(), GURL(),
+          text, std::u16string(), GURL(),
           message_center::NotifierId(
               message_center::NotifierType::SYSTEM_COMPONENT,
               kNotifierAccessibility),
@@ -1886,7 +1886,7 @@ void AccessibilityControllerImpl::
   NotifyAccessibilityStatusChanged();
 }
 
-base::string16 AccessibilityControllerImpl::GetBatteryDescription() const {
+std::u16string AccessibilityControllerImpl::GetBatteryDescription() const {
   // Pass battery status as string to callback function.
   return PowerStatus::Get()->GetAccessibleNameString(
       /*full_description=*/true);

ash/accessibility/accessibility_controller_impl.h

@@ -381,7 +381,7 @@ class ASH_EXPORT AccessibilityControllerImpl : public AccessibilityController,
   void ToggleDictationFromSource(DictationToggleSource source) override;
   void HandleAutoclickScrollableBoundsFound(
       gfx::Rect& bounds_in_screen) override;
-  base::string16 GetBatteryDescription() const override;
+  std::u16string GetBatteryDescription() const override;
   void SetVirtualKeyboardVisible(bool is_visible) override;
   void PerformAcceleratorAction(AcceleratorAction accelerator_action) override;
   void NotifyAccessibilityStatusChanged() override;

ash/accessibility/accessibility_controller_unittest.cc

@@ -914,9 +914,9 @@ TEST_F(AccessibilityControllerTest, SetDarkenScreen) {
 }
 
 TEST_F(AccessibilityControllerTest, ShowNotificationOnSpokenFeedback) {
-  const base::string16 kChromeVoxEnabledTitle =
+  const std::u16string kChromeVoxEnabledTitle =
       base::ASCIIToUTF16("ChromeVox enabled");
-  const base::string16 kChromeVoxEnabled =
+  const std::u16string kChromeVoxEnabled =
       base::ASCIIToUTF16("Press Ctrl + Alt + Z to disable spoken feedback.");
   AccessibilityControllerImpl* controller =
       Shell::Get()->accessibility_controller();
@@ -945,11 +945,11 @@ TEST_F(AccessibilityControllerTest, ShowNotificationOnSpokenFeedback) {
 
 TEST_F(AccessibilityControllerTest,
        ShowNotificationOnBrailleDisplayStateChanged) {
-  const base::string16 kBrailleConnected =
+  const std::u16string kBrailleConnected =
       base::ASCIIToUTF16("Braille display connected.");
-  const base::string16 kChromeVoxEnabled =
+  const std::u16string kChromeVoxEnabled =
       base::ASCIIToUTF16("Press Ctrl + Alt + Z to disable spoken feedback.");
-  const base::string16 kBrailleConnectedAndChromeVoxEnabledTitle =
+  const std::u16string kBrailleConnectedAndChromeVoxEnabledTitle =
       base::ASCIIToUTF16("Braille and ChromeVox are enabled");
   AccessibilityControllerImpl* controller =
       Shell::Get()->accessibility_controller();
@@ -962,7 +962,7 @@ TEST_F(AccessibilityControllerTest,
   message_center::NotificationList::Notifications notifications =
       MessageCenter::Get()->GetVisibleNotifications();
   ASSERT_EQ(1u, notifications.size());
-  EXPECT_EQ(base::string16(), (*notifications.begin())->title());
+  EXPECT_EQ(std::u16string(), (*notifications.begin())->title());
   EXPECT_EQ(kBrailleConnected, (*notifications.begin())->message());
 
   // Neither disconnecting a braille display, nor disabling spoken feedback

ash/ambient/ui/ambient_background_image_view.cc

@@ -118,7 +118,7 @@ void AmbientBackgroundImageView::UpdateImage(
 }
 
 void AmbientBackgroundImageView::UpdateImageDetails(
-    const base::string16& details) {
+    const std::u16string& details) {
   ambient_info_view_->UpdateImageDetails(details);
 }
 

ash/ambient/ui/ambient_background_image_view.h

@@ -46,7 +46,7 @@ class ASH_EXPORT AmbientBackgroundImageView : public views::View,
                    const gfx::ImageSkia& related_image);
 
   // Updates the details for the currently displayed image.
-  void UpdateImageDetails(const base::string16& details);
+  void UpdateImageDetails(const std::u16string& details);
 
   const gfx::ImageSkia& GetCurrentImage();
 

ash/ambient/ui/ambient_info_view.cc

@@ -39,7 +39,7 @@ AmbientInfoView::AmbientInfoView(AmbientViewDelegate* delegate)
 
 AmbientInfoView::~AmbientInfoView() = default;
 
-void AmbientInfoView::UpdateImageDetails(const base::string16& details) {
+void AmbientInfoView::UpdateImageDetails(const std::u16string& details) {
   details_label_->SetText(details);
 }
 

ash/ambient/ui/ambient_info_view.h

@@ -31,7 +31,7 @@ class ASH_EXPORT AmbientInfoView : public views::View {
   AmbientInfoView& operator=(AmbientInfoView&) = delete;
   ~AmbientInfoView() override;
 
-  void UpdateImageDetails(const base::string16& details);
+  void UpdateImageDetails(const std::u16string& details);
 
   void SetTextTransform(const gfx::Transform& transform);
 

ash/ambient/ui/glanceable_info_view.cc

@@ -107,7 +107,7 @@ void GlanceableInfoView::Show() {
   temperature_->SetText(GetTemperatureText());
 }
 
-base::string16 GlanceableInfoView::GetTemperatureText() const {
+std::u16string GlanceableInfoView::GetTemperatureText() const {
   AmbientBackendModel* ambient_backend_model =
       delegate_->GetAmbientBackendModel();
   if (ambient_backend_model->show_celsius()) {

ash/ambient/ui/glanceable_info_view.h

@@ -42,7 +42,7 @@ class GlanceableInfoView : public views::View,
  private:
   void InitLayout();
 
-  base::string16 GetTemperatureText() const;
+  std::u16string GetTemperatureText() const;
 
   // View for the time info. Owned by the view hierarchy.
   ash::tray::TimeView* time_view_ = nullptr;

ash/ambient/ui/media_string_view.cc

@@ -156,8 +156,8 @@ void MediaStringView::MediaSessionMetadataChanged(
   media_session::MediaMetadata session_metadata =
       metadata.value_or(media_session::MediaMetadata());
 
-  base::string16 media_string;
-  base::string16 middle_dot = base::UTF8ToUTF16(kMiddleDotSeparator);
+  std::u16string media_string;
+  std::u16string middle_dot = base::UTF8ToUTF16(kMiddleDotSeparator);
   if (!session_metadata.title.empty() && !session_metadata.artist.empty()) {
     media_string =
         session_metadata.title + middle_dot + session_metadata.artist;
@@ -168,7 +168,7 @@ void MediaStringView::MediaSessionMetadataChanged(
   }
 
   // Reset text and stop any ongoing animation.
-  media_text_->SetText(base::string16());
+  media_text_->SetText(std::u16string());
   media_text_->layer()->GetAnimator()->StopAnimating();
 
   media_text_->SetText(media_string);

ash/ambient/ui/media_string_view_unittest.cc

@@ -35,7 +35,7 @@ class MediaStringViewTest : public AmbientAshTestBase {
     AmbientAshTestBase::TearDown();
   }
 
-  const base::string16& GetText() {
+  const std::u16string& GetText() {
     return GetMediaStringViewTextLabel()->GetText();
   }
 };
@@ -50,7 +50,7 @@ TEST_F(MediaStringViewTest, ShowMediaTitleAndArtist) {
 
   SimulateMediaMetadataChanged(metadata);
 
-  const base::string16 expected_text = base::UTF8ToUTF16("title \u2022 artist");
+  const std::u16string expected_text = base::UTF8ToUTF16("title \u2022 artist");
   EXPECT_EQ(GetMediaStringViewTextLabel()->GetText(), expected_text);
 }
 

ash/app_list/app_list_controller_impl.cc

@@ -287,7 +287,7 @@ void AppListControllerImpl::SetSearchEngineIsGoogle(bool is_google) {
   search_model_.SetSearchEngineIsGoogle(is_google);
 }
 
-void AppListControllerImpl::UpdateSearchBox(const base::string16& text,
+void AppListControllerImpl::UpdateSearchBox(const std::u16string& text,
                                             bool initiated_by_user) {
   search_model_.search_box()->Update(text, initiated_by_user);
 }
@@ -1058,9 +1058,9 @@ void AppListControllerImpl::StartAssistant() {
       AssistantEntryPoint::kLauncherSearchBoxIcon);
 }
 
-void AppListControllerImpl::StartSearch(const base::string16& raw_query) {
+void AppListControllerImpl::StartSearch(const std::u16string& raw_query) {
   if (client_) {
-    base::string16 query;
+    std::u16string query;
     base::TrimWhitespace(raw_query, base::TRIM_ALL, &query);
     client_->StartSearch(query);
     auto* notifier = GetNotifier();
@@ -1270,11 +1270,11 @@ void AppListControllerImpl::OnSearchResultVisibilityChanged(
 }
 
 void AppListControllerImpl::NotifySearchResultsForLogging(
-    const base::string16& raw_query,
+    const std::u16string& raw_query,
     const SearchResultIdWithPositionIndices& results,
     int position_index) {
   if (client_) {
-    base::string16 query;
+    std::u16string query;
     base::TrimWhitespace(raw_query, base::TRIM_ALL, &query);
     client_->NotifySearchResultsForLogging(query, results, position_index);
   }
@@ -1596,7 +1596,7 @@ void AppListControllerImpl::ResetHomeLauncherIfShown() {
   presenter_.GetView()->CloseOpenedPage();
 
   // Refresh the suggestion chips with empty query.
-  StartSearch(base::string16());
+  StartSearch(std::u16string());
 }
 
 void AppListControllerImpl::UpdateLauncherContainer(
@@ -1642,7 +1642,7 @@ bool AppListControllerImpl::ShouldLauncherShowBehindApps() const {
 }
 
 int AppListControllerImpl::GetLastQueryLength() {
-  base::string16 query;
+  std::u16string query;
   base::TrimWhitespace(search_model_.search_box()->text(), base::TRIM_ALL,
                        &query);
   return query.length();

ash/app_list/app_list_controller_impl.h

@@ -100,7 +100,7 @@ class ASH_EXPORT AppListControllerImpl
                         const std::string& folder_id) override;
   void SetStatus(AppListModelStatus status) override;
   void SetSearchEngineIsGoogle(bool is_google) override;
-  void UpdateSearchBox(const base::string16& text,
+  void UpdateSearchBox(const std::u16string& text,
                        bool initiated_by_user) override;
   void PublishSearchResults(
       std::vector<std::unique_ptr<SearchResultMetadata>> results) override;
@@ -169,7 +169,7 @@ class ASH_EXPORT AppListControllerImpl
   SearchModel* GetSearchModel() override;
   AppListNotifier* GetNotifier() override;
   void StartAssistant() override;
-  void StartSearch(const base::string16& raw_query) override;
+  void StartSearch(const std::u16string& raw_query) override;
   void OpenSearchResult(const std::string& result_id,
                         int event_flags,
                         AppListLaunchedFrom launched_from,
@@ -205,7 +205,7 @@ class ASH_EXPORT AppListControllerImpl
   void OnSearchResultVisibilityChanged(const std::string& id,
                                        bool visibility) override;
   void NotifySearchResultsForLogging(
-      const base::string16& raw_query,
+      const std::u16string& raw_query,
       const SearchResultIdWithPositionIndices& results,
       int position_index) override;
   void MaybeIncreaseSuggestedContentInfoShownCount() override;

ash/app_list/app_list_controller_impl_unittest.cc

@@ -464,7 +464,7 @@ TEST_F(AppListControllerImplTest, MAYBE_CloseNotificationWithAppListShown) {
           message_center::NOTIFICATION_TYPE_BASE_FORMAT, notification_id,
           base::UTF8ToUTF16(notification_title),
           base::UTF8ToUTF16("test message"), gfx::Image(),
-          base::string16() /* display_source */, GURL(),
+          std::u16string() /* display_source */, GURL(),
           message_center::NotifierId(), message_center::RichNotificationData(),
           new message_center::NotificationDelegate()));
   base::RunLoop().RunUntilIdle();

ash/app_list/app_list_presenter_delegate_unittest.cc

@@ -353,7 +353,7 @@ class PopulatedAppListTest : public AshTestBase,
   }
 
   void UpdateFolderName(const std::string& name) {
-    base::string16 folder_name = base::UTF8ToUTF16(name);
+    std::u16string folder_name = base::UTF8ToUTF16(name);
     folder_view()->folder_header_view()->SetFolderNameForTest(folder_name);
     folder_view()->folder_header_view()->ContentsChanged(
         folder_view()->folder_header_view()->GetFolderNameViewForTest(),

ash/app_list/app_list_view_delegate.h

@@ -57,7 +57,7 @@ class ASH_PUBLIC_EXPORT AppListViewDelegate {
   // Invoked to start a new search. This collects a list of search results
   // matching the raw query, which is an unhandled string typed into the search
   // box by the user.
-  virtual void StartSearch(const base::string16& raw_query) = 0;
+  virtual void StartSearch(const std::u16string& raw_query) = 0;
 
   // Invoked to open the search result and log a click. If the result is
   // represented by a SuggestedChipView or is a zero state result,
@@ -157,7 +157,7 @@ class ASH_PUBLIC_EXPORT AppListViewDelegate {
   // |position_index| is the position index of the clicked item (if no item got
   // clicked, |position_index| will be -1).
   virtual void NotifySearchResultsForLogging(
-      const base::string16& raw_query,
+      const std::u16string& raw_query,
       const SearchResultIdWithPositionIndices& results,
       int position_index) = 0;
 

ash/app_list/model/search/search_box_model.cc

@@ -36,7 +36,7 @@ void SearchBoxModel::SetSearchEngineIsGoogle(bool is_google) {
     observer.SearchEngineChanged();
 }
 
-void SearchBoxModel::Update(const base::string16& text,
+void SearchBoxModel::Update(const std::u16string& text,
                             bool initiated_by_user) {
   if (text_ == text)
     return;

ash/app_list/model/search/search_box_model.h

@@ -37,15 +37,14 @@ class APP_LIST_MODEL_EXPORT SearchBoxModel {
 
   // Sets/gets the text for the search box's Textfield and the voice search
   // flag.
-  void Update(const base::string16& text,
-              bool initiated_by_user);
-  const base::string16& text() const { return text_; }
+  void Update(const std::u16string& text, bool initiated_by_user);
+  const std::u16string& text() const { return text_; }
 
   void AddObserver(SearchBoxModelObserver* observer);
   void RemoveObserver(SearchBoxModelObserver* observer);
 
  private:
-  base::string16 text_;
+  std::u16string text_;
   bool search_engine_is_google_ = false;
   bool is_tablet_mode_ = false;
   bool show_assistant_button_ = false;

ash/app_list/model/search/search_result.cc

@@ -38,7 +38,7 @@ void SearchResult::SetChipIcon(const gfx::ImageSkia& chip_icon) {
     observer.OnMetadataChanged();
 }
 
-void SearchResult::set_title(const base::string16& title) {
+void SearchResult::set_title(const std::u16string& title) {
   metadata_->title = title;
   for (auto& observer : observers_)
     observer.OnMetadataChanged();
@@ -56,7 +56,7 @@ void SearchResult::SetRating(float rating) {
     observer.OnMetadataChanged();
 }
 
-void SearchResult::SetFormattedPrice(const base::string16& formatted_price) {
+void SearchResult::SetFormattedPrice(const std::u16string& formatted_price) {
   metadata_->formatted_price = formatted_price;
   for (auto& observer : observers_)
     observer.OnMetadataChanged();

ash/app_list/model/search/search_result.h

@@ -57,34 +57,34 @@ class APP_LIST_MODEL_EXPORT SearchResult {
   const ui::ImageModel& badge_icon() const { return metadata_->badge_icon; }
   void SetBadgeIcon(const ui::ImageModel& badge_icon);
 
-  const base::string16& title() const { return metadata_->title; }
-  void set_title(const base::string16& title);
+  const std::u16string& title() const { return metadata_->title; }
+  void set_title(const std::u16string& title);
 
   const Tags& title_tags() const { return metadata_->title_tags; }
   void set_title_tags(const Tags& tags) { metadata_->title_tags = tags; }
 
-  const base::string16& details() const { return metadata_->details; }
-  void set_details(const base::string16& details) {
+  const std::u16string& details() const { return metadata_->details; }
+  void set_details(const std::u16string& details) {
     metadata_->details = details;
   }
 
   const Tags& details_tags() const { return metadata_->details_tags; }
   void set_details_tags(const Tags& tags) { metadata_->details_tags = tags; }
 
-  const base::string16& accessible_name() const {
+  const std::u16string& accessible_name() const {
     return metadata_->accessible_name;
   }
-  void set_accessible_name(const base::string16& name) {
+  void set_accessible_name(const std::u16string& name) {
     metadata_->accessible_name = name;
   }
 
   float rating() const { return metadata_->rating; }
   void SetRating(float rating);
 
-  const base::string16& formatted_price() const {
+  const std::u16string& formatted_price() const {
     return metadata_->formatted_price;
   }
-  void SetFormattedPrice(const base::string16& formatted_price);
+  void SetFormattedPrice(const std::u16string& formatted_price);
 
   const base::Optional<GURL>& query_url() const { return metadata_->query_url; }
   void set_query_url(const GURL& url) { metadata_->query_url = url; }

ash/app_list/test/app_list_test_view_delegate.cc

@@ -168,7 +168,7 @@ void AppListTestViewDelegate::OnSearchResultVisibilityChanged(
     bool visibility) {}
 
 void AppListTestViewDelegate::NotifySearchResultsForLogging(
-    const base::string16& raw_query,
+    const std::u16string& raw_query,
     const ash::SearchResultIdWithPositionIndices& results,
     int position_index) {}
 

ash/app_list/test/app_list_test_view_delegate.h

@@ -62,7 +62,7 @@ class AppListTestViewDelegate : public AppListViewDelegate,
   SearchModel* GetSearchModel() override;
   bool KeyboardTraversalEngaged() override;
   void StartAssistant() override {}
-  void StartSearch(const base::string16& raw_query) override {}
+  void StartSearch(const std::u16string& raw_query) override {}
   void OpenSearchResult(const std::string& result_id,
                         int event_flags,
                         ash::AppListLaunchedFrom launched_from,
@@ -95,7 +95,7 @@ class AppListTestViewDelegate : public AppListViewDelegate,
   void OnSearchResultVisibilityChanged(const std::string& id,
                                        bool visibility) override;
   void NotifySearchResultsForLogging(
-      const base::string16& raw_query,
+      const std::u16string& raw_query,
       const ash::SearchResultIdWithPositionIndices& results,
       int position_index) override;
   void MaybeIncreaseSuggestedContentInfoShownCount() override;

ash/app_list/test/test_app_list_client.h

@@ -25,7 +25,7 @@ class TestAppListClient : public AppListClient {
 
   // AppListClient:
   void OnAppListControllerDestroyed() override {}
-  void StartSearch(const base::string16& trimmed_query) override {}
+  void StartSearch(const std::u16string& trimmed_query) override {}
   void OpenSearchResult(const std::string& result_id,
                         int event_flags,
                         AppListLaunchedFrom launched_from,
@@ -60,7 +60,7 @@ class TestAppListClient : public AppListClient {
       const std::string& setting_name,
       const std::map<std::string, int>& values) override {}
   void NotifySearchResultsForLogging(
-      const base::string16& trimmed_query,
+      const std::u16string& trimmed_query,
       const SearchResultIdWithPositionIndices& results,
       int position_index) override {}
   AppListNotifier* GetNotifier() override;

ash/app_list/views/app_list_item_view.cc

@@ -511,9 +511,9 @@ const AppListConfig& AppListItemView::GetAppListConfig() const {
   return apps_grid_view_->GetAppListConfig();
 }
 
-void AppListItemView::SetItemName(const base::string16& display_name,
-                                  const base::string16& full_name) {
-  const base::string16 folder_name_placeholder =
+void AppListItemView::SetItemName(const std::u16string& display_name,
+                                  const std::u16string& full_name) {
+  const std::u16string folder_name_placeholder =
       ui::ResourceBundle::GetSharedInstance().GetLocalizedString(
           IDS_APP_LIST_FOLDER_NAME_PLACEHOLDER);
   if (is_folder_ && display_name.empty())
@@ -521,7 +521,7 @@ void AppListItemView::SetItemName(const base::string16& display_name,
   else
     title_->SetText(display_name);
 
-  tooltip_text_ = display_name == full_name ? base::string16() : full_name;
+  tooltip_text_ = display_name == full_name ? std::u16string() : full_name;
 
   // Use full name for accessibility.
   SetAccessibleName(
@@ -861,14 +861,14 @@ void AppListItemView::OnThemeChanged() {
   SchedulePaint();
 }
 
-base::string16 AppListItemView::GetTooltipText(const gfx::Point& p) const {
+std::u16string AppListItemView::GetTooltipText(const gfx::Point& p) const {
   // Use the label to generate a tooltip, so that it will consider its text
   // truncation in making the tooltip. We do not want the label itself to have a
   // tooltip, so we only temporarily enable it to get the tooltip text from the
   // label, then disable it again.
   title_->SetHandlesTooltips(true);
   title_->SetTooltipText(tooltip_text_);
-  base::string16 tooltip = title_->GetTooltipText(p);
+  std::u16string tooltip = title_->GetTooltipText(p);
   title_->SetHandlesTooltips(false);
   return tooltip;
 }

ash/app_list/views/app_list_item_view.h

@@ -57,8 +57,8 @@ class APP_LIST_EXPORT AppListItemView : public views::Button,
   // config state.
   void RefreshIcon();
 
-  void SetItemName(const base::string16& display_name,
-                   const base::string16& full_name);
+  void SetItemName(const std::u16string& display_name,
+                   const std::u16string& full_name);
 
   void GetAccessibleNodeData(ui::AXNodeData* node_data) override;
 
@@ -126,7 +126,7 @@ class APP_LIST_EXPORT AppListItemView : public views::Button,
   void OnThemeChanged() override;
 
   // views::View overrides:
-  base::string16 GetTooltipText(const gfx::Point& p) const override;
+  std::u16string GetTooltipText(const gfx::Point& p) const override;
 
   // When a dragged view enters this view, a preview circle is shown for
   // non-folder item while the icon is enlarged for folder item. When a
@@ -286,7 +286,7 @@ class APP_LIST_EXPORT AppListItemView : public views::Button,
   // Whether |context_menu_| was shown via key event.
   bool menu_show_initiated_from_key_ = false;
 
-  base::string16 tooltip_text_;
+  std::u16string tooltip_text_;
 
   // A timer to defer showing drag UI when mouse is pressed.
   base::OneShotTimer mouse_drag_timer_;

ash/app_list/views/app_list_main_view.cc

@@ -182,8 +182,8 @@ void AppListMainView::OnAppListStateChanged(AppListState new_state,
 }
 
 void AppListMainView::QueryChanged(SearchBoxViewBase* sender) {
-  base::string16 raw_query = search_model_->search_box()->text();
-  base::string16 query;
+  std::u16string raw_query = search_model_->search_box()->text();
+  std::u16string query;
   base::TrimWhitespace(raw_query, base::TRIM_ALL, &query);
   contents_view_->ShowSearchResults(search_box_view_->is_search_box_active() ||
                                     !query.empty());
@@ -199,8 +199,8 @@ void AppListMainView::ActiveChanged(SearchBoxViewBase* sender) {
   if (search_box_view_->is_search_box_active()) {
     // Show zero state suggestions when search box is activated with an empty
     // query.
-    base::string16 raw_query = search_model_->search_box()->text();
-    base::string16 query;
+    std::u16string raw_query = search_model_->search_box()->text();
+    std::u16string query;
     base::TrimWhitespace(raw_query, base::TRIM_ALL, &query);
     if (query.empty())
       search_box_view_->ShowZeroStateSuggestions();

ash/app_list/views/app_list_view.cc

@@ -1275,7 +1275,7 @@ void AppListView::MaybeCreateAccessibilityEvent(AppListViewState new_state) {
   if (!delegate_->AppListTargetVisibility())
     return;
 
-  base::string16 state_announcement;
+  std::u16string state_announcement;
 
   if (new_state == AppListViewState::kPeeking) {
     state_announcement = l10n_util::GetStringUTF16(

ash/app_list/views/app_list_view_unittest.cc

@@ -263,7 +263,7 @@ class AppListViewTest : public views::ViewsTestBase,
     views::Textfield* search_box =
         view_->app_list_main_view()->search_box_view()->search_box();
     // Set new text as if it is typed by a user.
-    search_box->SetText(base::string16());
+    search_box->SetText(std::u16string());
     search_box->InsertText(
         base::UTF8ToUTF16(text),
         ui::TextInputClient::InsertTextCursorBehavior::kMoveCursorAfterText);
@@ -657,7 +657,7 @@ class AppListViewFocusTest : public views::ViewsTestBase,
     TestLeftAndRightKeyTraversalOnTextfield(textfield);
 
     // Type something in textfield.
-    base::string16 text =
+    std::u16string text =
         text_rtl
             // Arabic word of "test".
             ? base::UTF8ToUTF16(
@@ -959,7 +959,7 @@ TEST_F(AppListViewFocusTest, CloseButtonClearsSearchOnEnter) {
   // Enter - it should clear the search box.
   SimulateKeyPress(ui::VKEY_RETURN, false /*shift_down*/);
   EXPECT_TRUE(search_box_view()->search_box()->HasFocus());
-  EXPECT_EQ(base::string16(), search_box_view()->search_box()->GetText());
+  EXPECT_EQ(std::u16string(), search_box_view()->search_box()->GetText());
   EXPECT_FALSE(search_box_view()->is_search_box_active());
   EXPECT_FALSE(contents_view()->search_results_page_view()->GetVisible());
   ResultSelectionController* selection_controller =
@@ -986,7 +986,7 @@ TEST_P(AppListViewFocusTest, LeftRightFocusTraversalInHalfState) {
   // Type something in search box to transition to HALF state and populate
   // fake search results.
   // Type something in textfield.
-  base::string16 text =
+  std::u16string text =
       is_rtl_
           // Arabic word of "test".
           ? base::UTF8ToUTF16(
@@ -1689,7 +1689,7 @@ TEST_F(AppListViewTest, EmptySearchTextStillPeeking) {
       view_->app_list_main_view()->search_box_view()->search_box();
 
   Show();
-  search_box->SetText(base::string16());
+  search_box->SetText(std::u16string());
 
   ASSERT_EQ(ash::AppListViewState::kPeeking, view_->app_list_state());
 }
@@ -1770,7 +1770,7 @@ TEST_F(AppListViewTest, TypingPeekingToHalf) {
       view_->app_list_main_view()->search_box_view()->search_box();
 
   Show();
-  search_box->SetText(base::string16());
+  search_box->SetText(std::u16string());
   search_box->InsertText(
       base::UTF8ToUTF16("nice"),
       ui::TextInputClient::InsertTextCursorBehavior::kMoveCursorAfterText);
@@ -1787,7 +1787,7 @@ TEST_F(AppListViewTest, TypingFullscreenToFullscreenSearch) {
   views::Textfield* search_box =
       view_->app_list_main_view()->search_box_view()->search_box();
 
-  search_box->SetText(base::string16());
+  search_box->SetText(std::u16string());
   search_box->InsertText(
       base::UTF8ToUTF16("https://youtu.be/dQw4w9WgXcQ"),
       ui::TextInputClient::InsertTextCursorBehavior::kMoveCursorAfterText);
@@ -1802,7 +1802,7 @@ TEST_F(AppListViewTest, TypingTabletModeFullscreenSearch) {
       view_->app_list_main_view()->search_box_view()->search_box();
 
   Show();
-  search_box->SetText(base::string16());
+  search_box->SetText(std::u16string());
   search_box->InsertText(
       base::UTF8ToUTF16("cool!"),
       ui::TextInputClient::InsertTextCursorBehavior::kMoveCursorAfterText);
@@ -2217,8 +2217,8 @@ TEST_F(AppListViewTest, DISABLED_SearchResultsTest) {
   view_->Layout();
   EXPECT_TRUE(IsStateShown(ash::AppListState::kStateApps));
 
-  base::string16 search_text = base::UTF8ToUTF16("test");
-  main_view->search_box_view()->search_box()->SetText(base::string16());
+  std::u16string search_text = base::UTF8ToUTF16("test");
+  main_view->search_box_view()->search_box()->SetText(std::u16string());
   main_view->search_box_view()->search_box()->InsertText(
       search_text,
       ui::TextInputClient::InsertTextCursorBehavior::kMoveCursorAfterText);
@@ -2238,8 +2238,8 @@ TEST_F(AppListViewTest, DISABLED_SearchResultsTest) {
   EXPECT_TRUE(CheckSearchBoxWidget(
       contents_view->GetSearchBoxBounds(ash::AppListState::kStateApps)));
 
-  base::string16 new_search_text = base::UTF8ToUTF16("apple");
-  main_view->search_box_view()->search_box()->SetText(base::string16());
+  std::u16string new_search_text = base::UTF8ToUTF16("apple");
+  main_view->search_box_view()->search_box()->SetText(std::u16string());
   main_view->search_box_view()->search_box()->InsertText(
       new_search_text,
       ui::TextInputClient::InsertTextCursorBehavior::kMoveCursorAfterText);
@@ -2293,8 +2293,8 @@ TEST_F(AppListViewTest, DISABLED_BackTest) {
   EXPECT_EQ(1, delegate_->dismiss_count());
 
   // Show the search results.
-  base::string16 new_search_text = base::UTF8ToUTF16("apple");
-  search_box_view->search_box()->SetText(base::string16());
+  std::u16string new_search_text = base::UTF8ToUTF16("apple");
+  search_box_view->search_box()->SetText(std::u16string());
   search_box_view->search_box()->InsertText(
       new_search_text,
       ui::TextInputClient::InsertTextCursorBehavior::kMoveCursorAfterText);

ash/app_list/views/apps_grid_view.cc

@@ -1882,10 +1882,10 @@ void AppsGridView::HandleKeyboardFoldering(ui::KeyboardCode key_code) {
   if (!CanMoveSelectedToTargetForKeyboardFoldering(target_index))
     return;
 
-  const base::string16 moving_view_title = selected_view_->title()->GetText();
+  const std::u16string moving_view_title = selected_view_->title()->GetText();
   AppListItemView* target_view =
       GetViewDisplayedAtSlotOnCurrentPage(target_index.slot);
-  const base::string16 target_view_title = target_view->title()->GetText();
+  const std::u16string target_view_title = target_view->title()->GetText();
   const bool target_view_is_folder = target_view->is_folder();
 
   AppListItemView* folder_item = MoveItemToFolder(selected_view_, target_index);
@@ -3755,7 +3755,7 @@ void AppsGridView::StartFolderDroppingAnimation(
 
   // Start animation.
   auto animation_view = std::make_unique<TopIconAnimationView>(
-      this, drag_item->GetIcon(GetAppListConfig().type()), base::string16(),
+      this, drag_item->GetIcon(GetAppListConfig().type()), std::u16string(),
       target_bounds, false, true);
   auto* animation_view_ptr =
       items_container_->AddChildView(std::move(animation_view));
@@ -3784,7 +3784,7 @@ void AppsGridView::MaybeCreateFolderDroppingAccessibilityEvent() {
 }
 
 void AppsGridView::AnnounceItemNotificationBadge(
-    const base::string16& selected_view_title) {
+    const std::u16string& selected_view_title) {
   // Set a11y name to announce the notification badge for the focused item.
   auto* announcement_view =
       contents_view_->app_list_view()->announcement_view();
@@ -3794,8 +3794,8 @@ void AppsGridView::AnnounceItemNotificationBadge(
   announcement_view->NotifyAccessibilityEvent(ax::mojom::Event::kAlert, true);
 }
 
-void AppsGridView::AnnounceFolderDrop(const base::string16& moving_view_title,
-                                      const base::string16& target_view_title,
+void AppsGridView::AnnounceFolderDrop(const std::u16string& moving_view_title,
+                                      const std::u16string& target_view_title,
                                       bool target_is_folder) {
   // Set a11y name to announce possible move to folder or creation of folder.
   auto* announcement_view =
@@ -3810,8 +3810,8 @@ void AppsGridView::AnnounceFolderDrop(const base::string16& moving_view_title,
 }
 
 void AppsGridView::AnnounceKeyboardFoldering(
-    const base::string16& moving_view_title,
-    const base::string16& target_view_title,
+    const std::u16string& moving_view_title,
+    const std::u16string& target_view_title,
     bool target_is_folder) {
   // Set a11y name to announce keyboard move to folder or creation of folder.
   auto* announcement_view =

ash/app_list/views/apps_grid_view.h

@@ -712,21 +712,21 @@ class APP_LIST_EXPORT AppsGridView : public views::View,
 
   // Modifies the announcement view to verbalize that the focused view has new
   // updates, based on the item having a notification badge.
-  void AnnounceItemNotificationBadge(const base::string16& selected_view_title);
+  void AnnounceItemNotificationBadge(const std::u16string& selected_view_title);
 
   // Modifies the announcement view to verbalize that the current drag will move
   // |moving_view_title| and create a folder or move it into an existing folder
   // with |target_view_title|.
-  void AnnounceFolderDrop(const base::string16& moving_view_title,
-                          const base::string16& target_view_title,
+  void AnnounceFolderDrop(const std::u16string& moving_view_title,
+                          const std::u16string& target_view_title,
                           bool target_is_folder);
 
   // Modifies the announcement view to vervalize that the most recent keyboard
   // foldering action has either moved |moving_view_title| into
   // |target_view_title| folder or that |moving_view_title| and
   // |target_view_title| have formed a new folder.
-  void AnnounceKeyboardFoldering(const base::string16& moving_view_title,
-                                 const base::string16& target_view_title,
+  void AnnounceKeyboardFoldering(const std::u16string& moving_view_title,
+                                 const std::u16string& target_view_title,
                                  bool target_is_folder);
 
   // During an app drag, creates an a11y event to verbalize drop target

ash/app_list/views/assistant/assistant_dialog_plate.cc

@@ -127,7 +127,7 @@ gfx::Size AssistantDialogPlate::CalculatePreferredSize() const {
 
 void AssistantDialogPlate::OnButtonPressed(AssistantButtonId button_id) {
   delegate_->OnDialogPlateButtonPressed(button_id);
-  textfield_->SetText(base::string16());
+  textfield_->SetText(std::u16string());
 }
 
 bool AssistantDialogPlate::HandleKeyEvent(views::Textfield* textfield,
@@ -153,7 +153,7 @@ bool AssistantDialogPlate::HandleKeyEvent(views::Textfield* textfield,
             base::UTF16ToUTF8(trimmed_text));
       }
 
-      textfield_->SetText(base::string16());
+      textfield_->SetText(std::u16string());
 
       return true;
     }
@@ -281,7 +281,7 @@ void AssistantDialogPlate::OnUiVisibilityChanged(
   } else {
     // When the Assistant UI is no longer visible we need to clear the dialog
     // plate so that text does not persist across Assistant launches.
-    textfield_->SetText(base::string16());
+    textfield_->SetText(std::u16string());
 
     HideKeyboardIfEnabled();
   }

ash/app_list/views/assistant/assistant_page_view_unittest.cc

@@ -854,7 +854,7 @@ TEST_F(AssistantPageViewTest, RememberAndShowHistory) {
 }
 
 TEST_F(AssistantPageViewTest, ShouldNotClearQueryWhenSwitchingToTabletMode) {
-  const base::string16 query_text = base::UTF8ToUTF16("unsubmitted query");
+  const std::u16string query_text = base::UTF8ToUTF16("unsubmitted query");
   ShowAssistantUiInTextMode();
   input_text_field()->SetText(query_text);
 

ash/app_list/views/folder_header_view.cc

@@ -217,7 +217,7 @@ class FolderHeaderView::FolderNameView : public views::Textfield,
 
   // Name of the folder when FolderNameView is focused, used to track folder
   // rename metric.
-  base::string16 starting_name_;
+  std::u16string starting_name_;
 
   // If the view is focused via a mouse press event, then selection will be
   // cleared by its mouse release. To address this, defer selecting all
@@ -295,8 +295,8 @@ void FolderHeaderView::Update() {
 
   folder_name_view_->SetVisible(folder_name_visible_);
   if (folder_name_visible_) {
-    base::string16 folder_name = base::UTF8ToUTF16(folder_item_->name());
-    base::string16 elided_folder_name = GetElidedFolderName(folder_name);
+    std::u16string folder_name = base::UTF8ToUTF16(folder_item_->name());
+    std::u16string elided_folder_name = GetElidedFolderName(folder_name);
     folder_name_view_->SetText(elided_folder_name);
     UpdateFolderNameAccessibleName();
   }
@@ -309,17 +309,17 @@ void FolderHeaderView::UpdateFolderNameAccessibleName() {
   // |folder_name_view_| is blank; otherwise, clear the accessible name, the
   // accessible state's value is set to be folder_name_view_->GetText() by
   // TextField.
-  base::string16 accessible_name = folder_name_view_->GetText().empty()
+  std::u16string accessible_name = folder_name_view_->GetText().empty()
                                        ? folder_name_placeholder_text_
-                                       : base::string16();
+                                       : std::u16string();
   folder_name_view_->SetAccessibleName(accessible_name);
 }
 
-const base::string16& FolderHeaderView::GetFolderNameForTest() {
+const std::u16string& FolderHeaderView::GetFolderNameForTest() {
   return folder_name_view_->GetText();
 }
 
-void FolderHeaderView::SetFolderNameForTest(const base::string16& name) {
+void FolderHeaderView::SetFolderNameForTest(const std::u16string& name) {
   folder_name_view_->SetText(name);
 }
 
@@ -348,17 +348,17 @@ int FolderHeaderView::GetMaxFolderNameWidth() const {
   return AppListConfig::instance().folder_header_max_width();
 }
 
-base::string16 FolderHeaderView::GetElidedFolderName(
-    const base::string16& folder_name) const {
+std::u16string FolderHeaderView::GetElidedFolderName(
+    const std::u16string& folder_name) const {
   // Enforce the maximum folder name length.
-  base::string16 name =
+  std::u16string name =
       folder_name.substr(0, AppListConfig::instance().max_folder_name_chars());
 
   // Get maximum text width for fitting into |folder_name_view_|.
   int text_width = std::min(GetMaxFolderNameWidth(), width()) -
                    folder_name_view_->GetCaretBounds().width() -
                    folder_name_view_->GetInsets().width();
-  base::string16 elided_name = gfx::ElideText(
+  std::u16string elided_name = gfx::ElideText(
       name, folder_name_view_->GetFontList(), text_width, gfx::ELIDE_TAIL);
   return elided_name;
 }
@@ -370,7 +370,7 @@ void FolderHeaderView::Layout() {
 
   gfx::Rect text_bounds(rect);
 
-  base::string16 text = folder_name_view_->GetText().empty()
+  std::u16string text = folder_name_view_->GetText().empty()
                             ? folder_name_placeholder_text_
                             : folder_name_view_->GetText();
   int text_width =
@@ -390,7 +390,7 @@ void FolderHeaderView::Layout() {
 }
 
 void FolderHeaderView::ContentsChanged(views::Textfield* sender,
-                                       const base::string16& new_contents) {
+                                       const std::u16string& new_contents) {
   // Temporarily remove from observer to ignore data change caused by us.
   if (!folder_item_)
     return;
@@ -445,7 +445,7 @@ void FolderHeaderView::SetPreviousCursorPositionForTest(
 }
 
 void FolderHeaderView::SetPreviousFolderNameForTest(
-    const base::string16& previous_name) {
+    const std::u16string& previous_name) {
   previous_folder_name_ = previous_name;
 }
 

ash/app_list/views/folder_header_view.h

@@ -58,8 +58,8 @@ class APP_LIST_EXPORT FolderHeaderView : public views::View,
   void UpdateFolderNameAccessibleName();
 
   // Gets and sets the folder name for test.
-  const base::string16& GetFolderNameForTest();
-  void SetFolderNameForTest(const base::string16& name);
+  const std::u16string& GetFolderNameForTest();
+  void SetFolderNameForTest(const std::u16string& name);
 
   // Returns true if folder name is enabled, only for testing use.
   bool IsFolderNameEnabledForTest() const;
@@ -67,7 +67,7 @@ class APP_LIST_EXPORT FolderHeaderView : public views::View,
   int GetMaxFolderNameWidth() const;
 
   // Returns elided folder name from |folder_name|.
-  base::string16 GetElidedFolderName(const base::string16& folder_name) const;
+  std::u16string GetElidedFolderName(const std::u16string& folder_name) const;
 
   // Returns whether |folder_name_view_| should clear focus based on
   // |key_event_|.
@@ -78,7 +78,7 @@ class APP_LIST_EXPORT FolderHeaderView : public views::View,
 
   // views::TextfieldController overrides:
   void ContentsChanged(views::Textfield* sender,
-                       const base::string16& new_contents) override;
+                       const std::u16string& new_contents) override;
   bool HandleKeyEvent(views::Textfield* sender,
                       const ui::KeyEvent& key_event) override;
   void OnBeforeUserAction(views::Textfield* sender) override;
@@ -90,11 +90,11 @@ class APP_LIST_EXPORT FolderHeaderView : public views::View,
   void SetPreviousCursorPositionForTest(const size_t cursor_position);
 
   // Sets the |previous_folder_name_|, only for testing use
-  void SetPreviousFolderNameForTest(const base::string16& previous_name);
+  void SetPreviousFolderNameForTest(const std::u16string& previous_name);
 
   // Used to restore the folder name if the new folder name is longer than the
   // max chars folder length allowed
-  base::Optional<base::string16> previous_folder_name_;
+  base::Optional<std::u16string> previous_folder_name_;
 
   // Used to restore the cursor position to its last known location when
   // resetting the folder name in textfield
@@ -104,7 +104,7 @@ class APP_LIST_EXPORT FolderHeaderView : public views::View,
 
   FolderNameView* folder_name_view_;  // Owned by views hierarchy.
 
-  const base::string16 folder_name_placeholder_text_;
+  const std::u16string folder_name_placeholder_text_;
 
   FolderHeaderViewDelegate* delegate_;
 

ash/app_list/views/folder_header_view_unittest.cc

@@ -89,7 +89,7 @@ class FolderHeaderViewTest : public views::ViewsTestBase {
 
  protected:
   void UpdateFolderName(const std::string& name) {
-    base::string16 folder_name = base::UTF8ToUTF16(name);
+    std::u16string folder_name = base::UTF8ToUTF16(name);
     folder_header_view_->SetFolderNameForTest(folder_name);
     folder_header_view_->ContentsChanged(textfield_.get(), folder_name);
   }
@@ -107,7 +107,7 @@ class FolderHeaderViewTest : public views::ViewsTestBase {
         previous_cursor_position);
   }
 
-  void UpdatePreviousFolderName(const base::string16& previous_name) {
+  void UpdatePreviousFolderName(const std::u16string& previous_name) {
     folder_header_view_->SetPreviousFolderNameForTest(previous_name);
   }
 
@@ -164,7 +164,7 @@ TEST_F(FolderHeaderViewTest, MaxFolderNameLength) {
   }
   std::string too_long_name = max_len_name + "a";
   UpdatePreviousCursorPosition(0);
-  UpdatePreviousFolderName(base::string16());
+  UpdatePreviousFolderName(std::u16string());
 
   // Expect that the folder name does not change, and does not truncate
   UpdateFolderName(too_long_name);

ash/app_list/views/privacy_info_view.cc

@@ -245,9 +245,9 @@ void PrivacyInfoView::InitInfoIcon() {
 }
 
 void PrivacyInfoView::InitText() {
-  const base::string16 link = l10n_util::GetStringUTF16(link_string_id_);
+  const std::u16string link = l10n_util::GetStringUTF16(link_string_id_);
   size_t offset;
-  const base::string16 text =
+  const std::u16string text =
       l10n_util::GetStringFUTF16(info_string_id_, link, &offset);
   text_view_ = AddChildView(std::make_unique<PrivacyTextView>(this));
   text_view_->SetText(text);
@@ -286,7 +286,7 @@ void PrivacyInfoView::InitCloseButton() {
                                                gfx::kGoogleGrey700));
   close_button->SetImageHorizontalAlignment(views::ImageButton::ALIGN_CENTER);
   close_button->SetImageVerticalAlignment(views::ImageButton::ALIGN_MIDDLE);
-  base::string16 close_button_label(l10n_util::GetStringUTF16(IDS_APP_CLOSE));
+  std::u16string close_button_label(l10n_util::GetStringUTF16(IDS_APP_CLOSE));
   close_button->SetAccessibleName(close_button_label);
   close_button->SetTooltipText(close_button_label);
   close_button->SetFocusBehavior(FocusBehavior::ALWAYS);

ash/app_list/views/remove_query_confirmation_dialog.cc

@@ -24,7 +24,7 @@ constexpr int kDialogWidth = 320;
 }  // namespace
 
 RemoveQueryConfirmationDialog::RemoveQueryConfirmationDialog(
-    const base::string16& query,
+    const std::u16string& query,
     RemovalConfirmationCallback confirm_callback)
     : confirm_callback_(std::move(confirm_callback)) {
   SetModalType(ui::MODAL_TYPE_WINDOW);

ash/app_list/views/remove_query_confirmation_dialog.h

@@ -21,7 +21,7 @@ class RemoveQueryConfirmationDialog : public views::DialogDelegateView {
   // associated result.
   using RemovalConfirmationCallback = base::OnceCallback<void(bool)>;
 
-  RemoveQueryConfirmationDialog(const base::string16& query,
+  RemoveQueryConfirmationDialog(const std::u16string& query,
                                 RemovalConfirmationCallback callback);
   ~RemoveQueryConfirmationDialog() override;
 

ash/app_list/views/result_selection_controller_unittest.cc

@@ -120,7 +120,7 @@ class TestContainer : public TestContainerDelegateHarness,
         result_view->GetActionsView()->SetActions(
             std::vector<SearchResult::Action>(
                 params.actions_per_result.value(),
-                SearchResult::Action(gfx::ImageSkia(), base::string16(),
+                SearchResult::Action(gfx::ImageSkia(), std::u16string(),
                                      false)));
         search_result_views_.emplace_back(std::move(result_view));
       } else {
@@ -1284,7 +1284,7 @@ TEST_F(ResultSelectionTest, ActionRemovedWhileSelected) {
   // Remove two trailing actions - the result action is de-selected.
   selected_view->AsResultViewWithActions()->GetActionsView()->SetActions(
       std::vector<SearchResult::Action>(
-          1, SearchResult::Action(gfx::ImageSkia(), base::string16(), false)));
+          1, SearchResult::Action(gfx::ImageSkia(), std::u16string(), false)));
   ASSERT_EQ(create_test_location(0, 1), GetCurrentLocation());
   EXPECT_TRUE(CurrentResultActionNotSelected());
 

ash/app_list/views/search_box_view.cc

@@ -75,8 +75,8 @@ float GetAssistantButtonOpacityForState(AppListState state) {
   return 1.f;
 }
 
-bool IsTrimmedQueryEmpty(const base::string16& query) {
-  base::string16 trimmed_query;
+bool IsTrimmedQueryEmpty(const std::u16string& query) {
+  std::u16string trimmed_query;
   base::TrimWhitespace(query, base::TrimPositions::TRIM_ALL, &trimmed_query);
   return trimmed_query.empty();
 }
@@ -244,7 +244,7 @@ void SearchBoxView::SetupCloseButton() {
                             AppListColorProvider::Get()->GetSearchBoxIconColor(
                                 gfx::kGoogleGrey700)));
   close->SetVisible(false);
-  base::string16 close_button_label(
+  std::u16string close_button_label(
       l10n_util::GetStringUTF16(IDS_APP_LIST_CLEAR_SEARCHBOX));
   close->SetAccessibleName(close_button_label);
   close->SetTooltipText(close_button_label);
@@ -258,7 +258,7 @@ void SearchBoxView::SetupBackButton() {
   back->SetImageHorizontalAlignment(views::ImageButton::ALIGN_CENTER);
   back->SetImageVerticalAlignment(views::ImageButton::ALIGN_MIDDLE);
   back->SetVisible(false);
-  base::string16 back_button_label(
+  std::u16string back_button_label(
       l10n_util::GetStringUTF16(IDS_APP_LIST_BACK));
   back->SetAccessibleName(back_button_label);
   back->SetTooltipText(back_button_label);
@@ -293,7 +293,7 @@ void SearchBoxView::RecordSearchBoxActivationHistogram(
 
 void SearchBoxView::OnSearchBoxActiveChanged(bool active) {
   if (active) {
-    search_box()->SetAccessibleName(base::string16());
+    search_box()->SetAccessibleName(std::u16string());
   } else {
     search_box()->SetAccessibleName(l10n_util::GetStringUTF16(
         is_tablet_mode_
@@ -399,7 +399,7 @@ SkColor SearchBoxView::GetBackgroundColorForState(AppListState state) const {
 void SearchBoxView::ShowZeroStateSuggestions() {
   base::RecordAction(
       base::UserMetricsAction("AppList_ShowZeroStateSuggestions"));
-  base::string16 empty_query;
+  std::u16string empty_query;
   ContentsChanged(search_box(), empty_query);
 }
 
@@ -439,7 +439,7 @@ void SearchBoxView::ProcessAutocomplete() {
   }
 
   // Current non-autocompleted text.
-  const base::string16& user_typed_text =
+  const std::u16string& user_typed_text =
       search_box()->GetText().substr(0, highlight_range_.start());
   if (last_key_pressed_ == ui::VKEY_BACK ||
       last_key_pressed_ == ui::VKEY_DELETE || IsArrowKey(last_key_pressed_) ||
@@ -450,8 +450,8 @@ void SearchBoxView::ProcessAutocomplete() {
     return;
   }
 
-  const base::string16& details = first_visible_result->details();
-  const base::string16& search_text = first_visible_result->title();
+  const std::u16string& details = first_visible_result->details();
+  const std::u16string& search_text = first_visible_result->title();
   if (base::StartsWith(details, user_typed_text,
                        base::CompareCase::INSENSITIVE_ASCII)) {
     // Current text in the search_box matches the first result's url.
@@ -523,7 +523,7 @@ void SearchBoxView::OnBeforeUserAction(views::Textfield* sender) {
 }
 
 void SearchBoxView::ContentsChanged(views::Textfield* sender,
-                                    const base::string16& new_contents) {
+                                    const std::u16string& new_contents) {
   if (IsTrimmedQueryEmpty(current_query_) && !IsSearchBoxTrimmedQueryEmpty()) {
     // User enters a new search query. Record the action.
     base::RecordAction(base::UserMetricsAction("AppList_SearchQueryStarted"));
@@ -540,11 +540,11 @@ void SearchBoxView::ContentsChanged(views::Textfield* sender,
 }
 
 void SearchBoxView::SetAutocompleteText(
-    const base::string16& autocomplete_text) {
+    const std::u16string& autocomplete_text) {
   if (!ShouldProcessAutocomplete())
     return;
 
-  const base::string16& current_text = search_box()->GetText();
+  const std::u16string& current_text = search_box()->GetText();
   // Currrent text is a prefix of autocomplete text.
   DCHECK(base::StartsWith(autocomplete_text, current_text,
                           base::CompareCase::INSENSITIVE_ASCII));
@@ -552,7 +552,7 @@ void SearchBoxView::SetAutocompleteText(
   if (autocomplete_text == current_text)
     return;
 
-  const base::string16& highlighted_text =
+  const std::u16string& highlighted_text =
       autocomplete_text.substr(highlight_range_.start());
 
   // Don't set autocomplete text if the highlighted text is the same as before.
@@ -581,7 +581,7 @@ void SearchBoxView::SetAutocompleteText(
   NotifyAccessibilityEvent(ax::mojom::Event::kValueChanged, true);
 }
 
-void SearchBoxView::UpdateQuery(const base::string16& new_query) {
+void SearchBoxView::UpdateQuery(const std::u16string& new_query) {
   search_box()->SetText(new_query);
   ContentsChanged(search_box(), new_query);
 }
@@ -670,7 +670,7 @@ bool SearchBoxView::HandleKeyEvent(views::Textfield* sender,
       selected_result->OnKeyEvent(&event);
     // Reset the selected result to the default result.
     selection_controller->ResetSelection(nullptr, true /* default_selection */);
-    search_box()->SetText(base::string16());
+    search_box()->SetText(std::u16string());
     return true;
   }
 
@@ -819,7 +819,7 @@ void SearchBoxView::SetupAssistantButton() {
       gfx::CreateVectorIcon(chromeos::kAssistantIcon, kSearchBoxIconSize,
                             AppListColorProvider::Get()->GetSearchBoxIconColor(
                                 gfx::kGoogleGrey700)));
-  base::string16 assistant_button_label(
+  std::u16string assistant_button_label(
       l10n_util::GetStringUTF16(IDS_APP_LIST_START_ASSISTANT));
   assistant->SetAccessibleName(assistant_button_label);
   assistant->SetTooltipText(assistant_button_label);

ash/app_list/views/search_box_view.h

@@ -99,7 +99,7 @@ class APP_LIST_EXPORT SearchBoxView : public SearchBoxViewBase,
   void ProcessAutocomplete();
 
   // Updates the search box with |new_query| and starts a new search.
-  void UpdateQuery(const base::string16& new_query);
+  void UpdateQuery(const std::u16string& new_query);
 
   // Clears the search query and de-activate the search box.
   void ClearSearchAndDeactivateSearchBox();
@@ -133,12 +133,12 @@ class APP_LIST_EXPORT SearchBoxView : public SearchBoxViewBase,
 
   // After verifying autocomplete text is valid, sets the current searchbox
   // text to the autocomplete text and sets the text highlight.
-  void SetAutocompleteText(const base::string16& autocomplete_text);
+  void SetAutocompleteText(const std::u16string& autocomplete_text);
 
   // Overridden from views::TextfieldController:
   void OnBeforeUserAction(views::Textfield* sender) override;
   void ContentsChanged(views::Textfield* sender,
-                       const base::string16& new_contents) override;
+                       const std::u16string& new_contents) override;
   bool HandleKeyEvent(views::Textfield* sender,
                       const ui::KeyEvent& key_event) override;
   bool HandleMouseEvent(views::Textfield* sender,
@@ -161,7 +161,7 @@ class APP_LIST_EXPORT SearchBoxView : public SearchBoxViewBase,
   // Clear highlight range.
   void ResetHighlightRange();
 
-  base::string16 current_query_;
+  std::u16string current_query_;
 
   // The range of highlighted text for autocomplete.
   gfx::Range highlight_range_;

ash/app_list/views/search_box_view_unittest.cc

@@ -123,13 +123,13 @@ class SearchBoxViewTest : public views::test::WidgetTest,
     if (::isalnum(static_cast<int>(key_code))) {
       char16_t character = ::tolower(static_cast<int>(key_code));
       view()->search_box()->InsertText(
-          base::string16(1, character),
+          std::u16string(1, character),
           ui::TextInputClient::InsertTextCursorBehavior::kMoveCursorAfterText);
     }
   }
 
   std::string GetLastQueryAndReset() {
-    base::string16 query = last_query_;
+    std::u16string query = last_query_;
     last_query_.clear();
     return base::UTF16ToUTF8(query);
   }
@@ -143,8 +143,8 @@ class SearchBoxViewTest : public views::test::WidgetTest,
   // Creates a SearchResult with the given parameters.
   void CreateSearchResult(ash::SearchResultDisplayType display_type,
                           double display_score,
-                          const base::string16& title,
-                          const base::string16& details) {
+                          const std::u16string& title,
+                          const std::u16string& details) {
     CreateSearchResultAt(results()->item_count(), display_type, display_score,
                          title, details);
   }
@@ -154,8 +154,8 @@ class SearchBoxViewTest : public views::test::WidgetTest,
   void CreateSearchResultAt(size_t index,
                             ash::SearchResultDisplayType display_type,
                             double display_score,
-                            const base::string16& title,
-                            const base::string16& details) {
+                            const std::u16string& title,
+                            const std::u16string& details) {
     auto search_result = std::make_unique<TestSearchResult>();
     search_result->set_result_id(base::NumberToString(++last_result_id_));
     search_result->set_display_type(display_type);
@@ -186,7 +186,7 @@ class SearchBoxViewTest : public views::test::WidgetTest,
   AppListView* app_list_view_ = nullptr;
   std::unique_ptr<SearchBoxView> view_;
   KeyPressCounterView* counter_view_;
-  base::string16 last_query_;
+  std::u16string last_query_;
   int query_changed_count_ = 0;
   int last_result_id_ = 0;
 
@@ -312,9 +312,9 @@ TEST_F(SearchBoxViewTest, ChangeSelectionWhileResultsAreChanging) {
   SetSearchBoxActive(true, ui::ET_UNKNOWN);
   view()->search_box()->SetText(base::ASCIIToUTF16("test"));
   CreateSearchResult(ash::SearchResultDisplayType::kList, 0.7,
-                     base::ASCIIToUTF16("tester"), base::string16());
+                     base::ASCIIToUTF16("tester"), std::u16string());
   CreateSearchResult(ash::SearchResultDisplayType::kList, 0.5,
-                     base::ASCIIToUTF16("testing"), base::string16());
+                     base::ASCIIToUTF16("testing"), std::u16string());
   base::RunLoop().RunUntilIdle();
 
   SearchResultPageView* const result_page_view =
@@ -330,7 +330,7 @@ TEST_F(SearchBoxViewTest, ChangeSelectionWhileResultsAreChanging) {
   // Add a new result - the selection controller is updated asynchronously, so
   // the result is expected to remain the same until the loop is run.
   CreateSearchResultAt(0, ash::SearchResultDisplayType::kList, 1.,
-                       base::ASCIIToUTF16("test"), base::string16());
+                       base::ASCIIToUTF16("test"), std::u16string());
   EXPECT_EQ(selection,
             result_page_view->result_selection_controller()->selected_result());
   EXPECT_EQ(base::ASCIIToUTF16("tester"), selection->result()->title());
@@ -365,9 +365,9 @@ TEST_F(SearchBoxViewTest, ChangeSelectionWhileResultsAreBeingRemoved) {
   SetSearchBoxActive(true, ui::ET_UNKNOWN);
   view()->search_box()->SetText(base::ASCIIToUTF16("test"));
   CreateSearchResult(ash::SearchResultDisplayType::kList, 0.7,
-                     base::ASCIIToUTF16("tester"), base::string16());
+                     base::ASCIIToUTF16("tester"), std::u16string());
   CreateSearchResult(ash::SearchResultDisplayType::kList, 0.5,
-                     base::ASCIIToUTF16("testing"), base::string16());
+                     base::ASCIIToUTF16("testing"), std::u16string());
   base::RunLoop().RunUntilIdle();
 
   SearchResultPageView* const result_page_view =
@@ -385,7 +385,7 @@ TEST_F(SearchBoxViewTest, ChangeSelectionWhileResultsAreBeingRemoved) {
   // the loop is run.
   results()->RemoveAll();
   CreateSearchResult(ash::SearchResultDisplayType::kList, 1.,
-                     base::ASCIIToUTF16("test"), base::string16());
+                     base::ASCIIToUTF16("test"), std::u16string());
   EXPECT_EQ(selection,
             result_page_view->result_selection_controller()->selected_result());
   EXPECT_FALSE(selection->result());
@@ -414,9 +414,9 @@ TEST_F(SearchBoxViewTest, UserSelectionNotOverridenByNewResults) {
   SetSearchBoxActive(true, ui::ET_UNKNOWN);
   view()->search_box()->SetText(base::ASCIIToUTF16("test"));
   CreateSearchResult(ash::SearchResultDisplayType::kList, 0.7,
-                     base::ASCIIToUTF16("tester"), base::string16());
+                     base::ASCIIToUTF16("tester"), std::u16string());
   CreateSearchResult(ash::SearchResultDisplayType::kList, 0.5,
-                     base::ASCIIToUTF16("testing"), base::string16());
+                     base::ASCIIToUTF16("testing"), std::u16string());
   base::RunLoop().RunUntilIdle();
 
   SearchResultPageView* const result_page_view =
@@ -438,7 +438,7 @@ TEST_F(SearchBoxViewTest, UserSelectionNotOverridenByNewResults) {
 
   // Add a new result - verify the selected result remains the same.
   CreateSearchResultAt(0, ash::SearchResultDisplayType::kList, 0.9,
-                       base::ASCIIToUTF16("test1"), base::string16());
+                       base::ASCIIToUTF16("test1"), std::u16string());
   // Finish results update.
   base::RunLoop().RunUntilIdle();
 
@@ -448,7 +448,7 @@ TEST_F(SearchBoxViewTest, UserSelectionNotOverridenByNewResults) {
 
   // Add a new result at the end, and verify the selection stays the same.
   CreateSearchResult(ash::SearchResultDisplayType::kList, 0.2,
-                     base::ASCIIToUTF16("testing almost"), base::string16());
+                     base::ASCIIToUTF16("testing almost"), std::u16string());
   base::RunLoop().RunUntilIdle();
 
   selection =
@@ -480,7 +480,7 @@ TEST_F(SearchBoxViewTest, UserSelectionNotOverridenByNewResults) {
 
   // New result can override the default selection.
   CreateSearchResultAt(0, ash::SearchResultDisplayType::kList, 1.0,
-                       base::ASCIIToUTF16("test"), base::string16());
+                       base::ASCIIToUTF16("test"), std::u16string());
   base::RunLoop().RunUntilIdle();
 
   selection =
@@ -493,9 +493,9 @@ TEST_F(SearchBoxViewTest,
   SetSearchBoxActive(true, ui::ET_UNKNOWN);
   view()->search_box()->SetText(base::ASCIIToUTF16("test"));
   CreateSearchResult(ash::SearchResultDisplayType::kList, 0.7,
-                     base::ASCIIToUTF16("tester"), base::string16());
+                     base::ASCIIToUTF16("tester"), std::u16string());
   CreateSearchResult(ash::SearchResultDisplayType::kList, 0.5,
-                     base::ASCIIToUTF16("testing"), base::string16());
+                     base::ASCIIToUTF16("testing"), std::u16string());
   base::RunLoop().RunUntilIdle();
 
   SearchResultPageView* const result_page_view =
@@ -518,7 +518,7 @@ TEST_F(SearchBoxViewTest,
   // Add a new result in a tile container - verify the selected result remains
   // the same.
   CreateSearchResultAt(0, ash::SearchResultDisplayType::kTile, 0.9,
-                       base::ASCIIToUTF16("test tile"), base::string16());
+                       base::ASCIIToUTF16("test tile"), std::u16string());
   // Finish results update.
   base::RunLoop().RunUntilIdle();
 
@@ -528,7 +528,7 @@ TEST_F(SearchBoxViewTest,
 
   // Add a new result at the end, and verify the selection stays the same.
   CreateSearchResult(ash::SearchResultDisplayType::kList, 0.2,
-                     base::ASCIIToUTF16("testing almost"), base::string16());
+                     base::ASCIIToUTF16("testing almost"), std::u16string());
   base::RunLoop().RunUntilIdle();
 
   selection =
@@ -554,7 +554,7 @@ TEST_F(SearchBoxViewTest,
 
   // New result can override the default selection.
   CreateSearchResultAt(0, ash::SearchResultDisplayType::kTile, 1.0,
-                       base::ASCIIToUTF16("test"), base::string16());
+                       base::ASCIIToUTF16("test"), std::u16string());
   base::RunLoop().RunUntilIdle();
 
   selection =
@@ -567,9 +567,9 @@ TEST_F(SearchBoxViewTest,
 TEST_F(SearchBoxViewTest, ResetSelectionAfterResettingSearchBox) {
   SetSearchBoxActive(true, ui::ET_UNKNOWN);
   CreateSearchResult(ash::SearchResultDisplayType::kList, 0.7,
-                     base::ASCIIToUTF16("test1"), base::string16());
+                     base::ASCIIToUTF16("test1"), std::u16string());
   CreateSearchResult(ash::SearchResultDisplayType::kList, 0.5,
-                     base::ASCIIToUTF16("test2"), base::string16());
+                     base::ASCIIToUTF16("test2"), std::u16string());
   base::RunLoop().RunUntilIdle();
 
   SearchResultPageView* const result_page_view =
@@ -647,7 +647,7 @@ TEST_F(SearchBoxViewTest, NavigateSuggestedContentInfo) {
   // Set up the search box.
   SetSearchBoxActive(true, ui::ET_UNKNOWN);
   CreateSearchResult(ash::SearchResultDisplayType::kList, 1.0,
-                     base::ASCIIToUTF16("test"), base::string16());
+                     base::ASCIIToUTF16("test"), std::u16string());
   base::RunLoop().RunUntilIdle();
 
   SearchResultPageView* const result_page_view =
@@ -701,7 +701,7 @@ TEST_F(SearchBoxViewTest, KeyboardEventClosesSuggestedContentInfo) {
   // Set up the search box.
   SetSearchBoxActive(true, ui::ET_UNKNOWN);
   CreateSearchResult(ash::SearchResultDisplayType::kList, 1.0,
-                     base::ASCIIToUTF16("test"), base::string16());
+                     base::ASCIIToUTF16("test"), std::u16string());
   base::RunLoop().RunUntilIdle();
 
   EXPECT_EQ(contents_view->search_results_page_view()
@@ -731,7 +731,7 @@ TEST_F(SearchBoxViewTest, SuggestedContentActionNotOverriddenByNewResults) {
   // Set up the search box.
   SetSearchBoxActive(true, ui::ET_UNKNOWN);
   CreateSearchResult(ash::SearchResultDisplayType::kList, 1.0,
-                     base::ASCIIToUTF16("test"), base::string16());
+                     base::ASCIIToUTF16("test"), std::u16string());
   base::RunLoop().RunUntilIdle();
 
   ResultSelectionController* const selection_controller =
@@ -749,7 +749,7 @@ TEST_F(SearchBoxViewTest, SuggestedContentActionNotOverriddenByNewResults) {
   // Create a new search result. The privacy view should have no actions
   // remaining.
   CreateSearchResult(ash::SearchResultDisplayType::kList, 0.5,
-                     base::ASCIIToUTF16("testing"), base::string16());
+                     base::ASCIIToUTF16("testing"), std::u16string());
   base::RunLoop().RunUntilIdle();
 
   KeyPress(ui::VKEY_TAB);
@@ -773,7 +773,7 @@ TEST_F(SearchBoxViewTest, SuggestedContentSelectionDoesNotChangeSearchBoxText) {
   // Set up the search box.
   SetSearchBoxActive(true, ui::ET_UNKNOWN);
   CreateSearchResult(ash::SearchResultDisplayType::kList, 1.0,
-                     base::ASCIIToUTF16("test"), base::string16());
+                     base::ASCIIToUTF16("test"), std::u16string());
   base::RunLoop().RunUntilIdle();
 
   ResultSelectionController* const selection_controller =
@@ -872,7 +872,7 @@ class SearchBoxViewAutocompleteTest
   void SetupAutocompleteBehaviorTest() {
     // Add a search result with a non-empty title field.
     CreateSearchResult(ash::SearchResultDisplayType::kList, 1.0,
-                       base::ASCIIToUTF16("hello world!"), base::string16());
+                       base::ASCIIToUTF16("hello world!"), std::u16string());
     base::RunLoop().RunUntilIdle();
 
     // Send H, E to the SearchBoxView textfield, then trigger an autocomplete.
@@ -884,7 +884,7 @@ class SearchBoxViewAutocompleteTest
   // Clears all existing text from search_box() and all existing SearchResults
   // from results().
   void ResetAutocompleteBehaviorTest() {
-    view()->search_box()->SetText(base::string16());
+    view()->search_box()->SetText(std::u16string());
     results()->RemoveAll();
   }
 
@@ -972,9 +972,9 @@ TEST_F(SearchBoxViewAutocompleteTest,
   // Add two SearchResults, one tile and one list result. Initialize their title
   // field to a non-empty string.
   CreateSearchResult(ash::SearchResultDisplayType::kList, 1.0,
-                     base::ASCIIToUTF16("hello list"), base::string16());
+                     base::ASCIIToUTF16("hello list"), std::u16string());
   CreateSearchResult(ash::SearchResultDisplayType::kTile, 0.5,
-                     base::ASCIIToUTF16("hello tile"), base::string16());
+                     base::ASCIIToUTF16("hello tile"), std::u16string());
   base::RunLoop().RunUntilIdle();
 
   // Send H, E to the SearchBoxView textfield, then trigger an autocomplete.
@@ -994,9 +994,9 @@ TEST_F(SearchBoxViewAutocompleteTest,
   // Add two SearchResults, one tile and one list result. Initialize their title
   // field to a non-empty string.
   CreateSearchResult(ash::SearchResultDisplayType::kTile, 1.0,
-                     base::ASCIIToUTF16("hello tile"), base::string16());
+                     base::ASCIIToUTF16("hello tile"), std::u16string());
   CreateSearchResult(ash::SearchResultDisplayType::kList, 0.5,
-                     base::ASCIIToUTF16("hello list"), base::string16());
+                     base::ASCIIToUTF16("hello list"), std::u16string());
   base::RunLoop().RunUntilIdle();
 
   // Send H, E to the SearchBoxView textfield, then trigger an autocomplete.
@@ -1015,9 +1015,9 @@ TEST_F(SearchBoxViewAutocompleteTest,
   // Add two SearchResults, one tile and one list result. The tile should
   // display first, despite having a lower score. Initialize their details field
   // to a non-empty string.
-  CreateSearchResult(ash::SearchResultDisplayType::kList, 1.0, base::string16(),
+  CreateSearchResult(ash::SearchResultDisplayType::kList, 1.0, std::u16string(),
                      base::ASCIIToUTF16("hello list"));
-  CreateSearchResult(ash::SearchResultDisplayType::kTile, 0.5, base::string16(),
+  CreateSearchResult(ash::SearchResultDisplayType::kTile, 0.5, std::u16string(),
                      base::ASCIIToUTF16("hello tile"));
   base::RunLoop().RunUntilIdle();
 
@@ -1036,9 +1036,9 @@ TEST_F(SearchBoxViewAutocompleteTest,
        SearchBoxAutocompletesTopTileResultDetails) {
   // Add two SearchResults, one tile and one list result. Initialize their
   // details field to a non-empty string.
-  CreateSearchResult(ash::SearchResultDisplayType::kTile, 1.0, base::string16(),
+  CreateSearchResult(ash::SearchResultDisplayType::kTile, 1.0, std::u16string(),
                      base::ASCIIToUTF16("hello tile"));
-  CreateSearchResult(ash::SearchResultDisplayType::kList, 0.5, base::string16(),
+  CreateSearchResult(ash::SearchResultDisplayType::kList, 0.5, std::u16string(),
                      base::ASCIIToUTF16("hello list"));
   base::RunLoop().RunUntilIdle();
 
@@ -1073,7 +1073,7 @@ TEST_F(SearchBoxViewAutocompleteTest,
 TEST_F(SearchBoxViewAutocompleteTest, SearchBoxAutocompletesAcceptsNextChar) {
   // Add a search result with a non-empty title field.
   CreateSearchResult(ash::SearchResultDisplayType::kList, 1.0,
-                     base::ASCIIToUTF16("hello world!"), base::string16());
+                     base::ASCIIToUTF16("hello world!"), std::u16string());
   base::RunLoop().RunUntilIdle();
 
   // Send H, E to the SearchBoxView textfield, then trigger an autocomplete.
@@ -1083,7 +1083,7 @@ TEST_F(SearchBoxViewAutocompleteTest, SearchBoxAutocompletesAcceptsNextChar) {
 
   // After typing L, the highlighted text will be replaced by L.
   KeyPress(ui::VKEY_L);
-  base::string16 selected_text = view()->search_box()->GetSelectedText();
+  std::u16string selected_text = view()->search_box()->GetSelectedText();
   EXPECT_EQ(view()->search_box()->GetText(), base::ASCIIToUTF16("hel"));
   EXPECT_EQ(base::ASCIIToUTF16(""), selected_text);
 
@@ -1111,7 +1111,7 @@ TEST_F(SearchBoxViewAutocompleteTest, SearchBoxAcceptsAutocompleteForClickTap) {
 TEST_F(SearchBoxViewAutocompleteTest, SearchBoxAutocompletesNotHandledForIME) {
   // Add a search result with a non-empty title field.
   CreateSearchResult(ash::SearchResultDisplayType::kList, 1.0,
-                     base::ASCIIToUTF16("hello world!"), base::string16());
+                     base::ASCIIToUTF16("hello world!"), std::u16string());
   base::RunLoop().RunUntilIdle();
 
   // Simulate uncomposited text. The autocomplete should be handled.
@@ -1120,11 +1120,11 @@ TEST_F(SearchBoxViewAutocompleteTest, SearchBoxAutocompletesNotHandledForIME) {
   view()->set_highlight_range_for_test(gfx::Range(2, 2));
   view()->ProcessAutocomplete();
 
-  base::string16 selected_text = view()->search_box()->GetSelectedText();
+  std::u16string selected_text = view()->search_box()->GetSelectedText();
   EXPECT_EQ(view()->search_box()->GetText(),
             base::ASCIIToUTF16("hello world!"));
   EXPECT_EQ(base::ASCIIToUTF16("llo world!"), selected_text);
-  view()->search_box()->SetText(base::string16());
+  view()->search_box()->SetText(std::u16string());
 
   // Simulate IME composition text. The autocomplete should not be handled.
   ui::CompositionText composition_text;

ash/app_list/views/search_result_base_view.cc

@@ -82,14 +82,14 @@ void SearchResultBaseView::OnResultDestroying() {
   SetResult(nullptr);
 }
 
-base::string16 SearchResultBaseView::ComputeAccessibleName() const {
+std::u16string SearchResultBaseView::ComputeAccessibleName() const {
   if (!result())
-    return base::string16();
+    return std::u16string();
 
   if (!result()->accessible_name().empty())
     return result()->accessible_name();
 
-  base::string16 accessible_name = result()->title();
+  std::u16string accessible_name = result()->title();
   if (!result()->title().empty() && !result()->details().empty())
     accessible_name += base::ASCIIToUTF16(", ");
   accessible_name += result()->details();

ash/app_list/views/search_result_base_view.h

@@ -63,7 +63,7 @@ class APP_LIST_EXPORT SearchResultBaseView : public views::Button,
   void OnResultDestroying() override;
 
   // Computes the button's spoken feedback name.
-  virtual base::string16 ComputeAccessibleName() const;
+  virtual std::u16string ComputeAccessibleName() const;
 
   // Clears the result without calling |OnResultChanged| or |OnResultChanging|
   void ClearResult();

ash/app_list/views/search_result_page_view.cc

@@ -262,8 +262,8 @@ void SearchResultPageView::GetAccessibleNodeData(ui::AXNodeData* node_data) {
 
   node_data->role = ax::mojom::Role::kListBox;
 
-  base::string16 value;
-  base::string16 query = search_model_->search_box()->text();
+  std::u16string value;
+  std::u16string query = search_model_->search_box()->text();
   if (!query.empty()) {
     if (last_search_result_count_ == 1) {
       value = l10n_util::GetStringFUTF16(

ash/app_list/views/search_result_suggestion_chip_view.cc

@@ -190,29 +190,29 @@ void SearchResultSuggestionChipView::SetIcon(const gfx::ImageSkia& icon) {
   icon_view_->SetVisible(true);
 }
 
-void SearchResultSuggestionChipView::SetText(const base::string16& text) {
+void SearchResultSuggestionChipView::SetText(const std::u16string& text) {
   text_view_->SetText(text);
   gfx::Size size = text_view_->CalculatePreferredSize();
   size.set_width(std::min(kMaxTextWidth, size.width()));
   text_view_->SetPreferredSize(size);
 }
 
-const base::string16& SearchResultSuggestionChipView::GetText() const {
+const std::u16string& SearchResultSuggestionChipView::GetText() const {
   return text_view_->GetText();
 }
 
 void SearchResultSuggestionChipView::UpdateSuggestionChipView() {
   if (!result()) {
     SetIcon(gfx::ImageSkia());
-    SetText(base::string16());
-    SetAccessibleName(base::string16());
+    SetText(std::u16string());
+    SetAccessibleName(std::u16string());
     return;
   }
 
   SetIcon(result()->chip_icon());
   SetText(result()->title());
 
-  base::string16 accessible_name = result()->title();
+  std::u16string accessible_name = result()->title();
   if (result()->id() == kInternalAppIdContinueReading) {
     accessible_name = l10n_util::GetStringFUTF16(
         IDS_APP_LIST_CONTINUE_READING_ACCESSIBILE_NAME, accessible_name);
@@ -242,7 +242,7 @@ void SearchResultSuggestionChipView::InitLayout() {
   text_view_->SetAutoColorReadabilityEnabled(false);
   text_view_->SetSubpixelRenderingEnabled(false);
   text_view_->SetFontList(AppListConfig::instance().app_title_font());
-  SetText(base::string16());
+  SetText(std::u16string());
   text_view_->SetEnabledColor(
       AppListColorProvider::Get()->GetSuggestionChipTextColor());
 }

ash/app_list/views/search_result_suggestion_chip_view.h

@@ -60,8 +60,8 @@ class APP_LIST_EXPORT SearchResultSuggestionChipView
 
   void SetIcon(const gfx::ImageSkia& icon);
 
-  void SetText(const base::string16& text);
-  const base::string16& GetText() const;
+  void SetText(const std::u16string& text);
+  const std::u16string& GetText() const;
 
  private:
   // Updates the suggestion chip view's title and icon.

ash/app_list/views/search_result_tile_item_list_view.cc

@@ -194,7 +194,7 @@ int SearchResultTileItemListView::DoUpdate() {
 
   // Track play store results and start the timer for recording their impression
   // UMA metrics.
-  base::string16 user_typed_query = GetUserTypedQuery();
+  std::u16string user_typed_query = GetUserTypedQuery();
   if (found_playstore_results && user_typed_query != recent_playstore_query_) {
     recent_playstore_query_ = user_typed_query;
     playstore_impression_timer_.Stop();
@@ -250,8 +250,8 @@ int SearchResultTileItemListView::DoUpdate() {
 }
 
 std::vector<SearchResult*> SearchResultTileItemListView::GetDisplayResults() {
-  base::string16 raw_query = search_box_->GetText();
-  base::string16 query;
+  std::u16string raw_query = search_box_->GetText();
+  std::u16string query;
   base::TrimWhitespace(raw_query, base::TRIM_ALL, &query);
 
   // We ask for |max_search_result_tiles_| policy tile results first,
@@ -315,13 +315,13 @@ std::vector<SearchResult*> SearchResultTileItemListView::GetDisplayResults() {
   return display_results;
 }
 
-base::string16 SearchResultTileItemListView::GetUserTypedQuery() {
-  base::string16 search_box_text = search_box_->GetText();
+std::u16string SearchResultTileItemListView::GetUserTypedQuery() {
+  std::u16string search_box_text = search_box_->GetText();
   gfx::Range range = search_box_->GetSelectedRange();
-  base::string16 raw_query = range.is_empty()
+  std::u16string raw_query = range.is_empty()
                                  ? search_box_text
                                  : search_box_text.substr(0, range.start());
-  base::string16 query;
+  std::u16string query;
   base::TrimWhitespace(raw_query, base::TRIM_ALL, &query);
   return query;
 }

ash/app_list/views/search_result_tile_item_list_view.h

@@ -57,7 +57,7 @@ class APP_LIST_EXPORT SearchResultTileItemListView
 
   std::vector<SearchResult*> GetDisplayResults();
 
-  base::string16 GetUserTypedQuery();
+  std::u16string GetUserTypedQuery();
 
   void OnPlayStoreImpressionTimer();
 
@@ -73,7 +73,7 @@ class APP_LIST_EXPORT SearchResultTileItemListView
   views::Textfield* search_box_ = nullptr;
   views::BoxLayout* layout_ = nullptr;
 
-  base::string16 recent_playstore_query_;
+  std::u16string recent_playstore_query_;
 
   base::OneShotTimer playstore_impression_timer_;
 

ash/app_list/views/search_result_tile_item_view.cc

@@ -198,8 +198,8 @@ void SearchResultTileItemView::OnResultChanged() {
   UpdateAccessibleName();
 }
 
-base::string16 SearchResultTileItemView::ComputeAccessibleName() const {
-  base::string16 accessible_name;
+std::u16string SearchResultTileItemView::ComputeAccessibleName() const {
+  std::u16string accessible_name;
   if (!result()->accessible_name().empty())
     return result()->accessible_name();
 
@@ -440,7 +440,7 @@ void SearchResultTileItemView::SetBadgeIcon(const ui::ImageModel& badge_icon,
   badge_->SetVisible(true);
 }
 
-void SearchResultTileItemView::SetTitle(const base::string16& title) {
+void SearchResultTileItemView::SetTitle(const std::u16string& title) {
   title_->SetText(title);
 }
 
@@ -459,7 +459,7 @@ void SearchResultTileItemView::SetRating(float rating) {
   rating_star_->SetVisible(true);
 }
 
-void SearchResultTileItemView::SetPrice(const base::string16& price) {
+void SearchResultTileItemView::SetPrice(const std::u16string& price) {
   if (!price_)
     return;
 
@@ -592,14 +592,14 @@ gfx::Size SearchResultTileItemView::CalculatePreferredSize() const {
                    AppListConfig::instance().search_tile_height());
 }
 
-base::string16 SearchResultTileItemView::GetTooltipText(
+std::u16string SearchResultTileItemView::GetTooltipText(
     const gfx::Point& p) const {
   // Use the label to generate a tooltip, so that it will consider its text
   // truncation in making the tooltip. We do not want the label itself to have a
   // tooltip, so we only temporarily enable it to get the tooltip text from the
   // label, then disable it again.
   title_->SetHandlesTooltips(true);
-  base::string16 tooltip = title_->GetTooltipText(p);
+  std::u16string tooltip = title_->GetTooltipText(p);
   title_->SetHandlesTooltips(false);
   return tooltip;
 }

ash/app_list/views/search_result_tile_item_view.h

@@ -40,7 +40,7 @@ class APP_LIST_EXPORT SearchResultTileItemView
   void OnResultChanged() override;
 
   // Overridden from SearchResultBaseView:
-  base::string16 ComputeAccessibleName() const override;
+  std::u16string ComputeAccessibleName() const override;
 
   // Informs the SearchResultTileItemView of its parent's background color. The
   // controls within the SearchResultTileItemView will adapt to suit the given
@@ -88,9 +88,9 @@ class APP_LIST_EXPORT SearchResultTileItemView
   void SetIcon(const gfx::ImageSkia& icon);
   void SetBadgeIcon(const ui::ImageModel& badge_icon,
                     bool use_badge_icon_background);
-  void SetTitle(const base::string16& title);
+  void SetTitle(const std::u16string& title);
   void SetRating(float rating);
-  void SetPrice(const base::string16& price);
+  void SetPrice(const std::u16string& price);
 
   AppListMenuModelAdapter::AppListViewAppType GetAppType() const;
 
@@ -106,7 +106,7 @@ class APP_LIST_EXPORT SearchResultTileItemView
   void Layout() override;
   const char* GetClassName() const override;
   gfx::Size CalculatePreferredSize() const override;
-  base::string16 GetTooltipText(const gfx::Point& p) const override;
+  std::u16string GetTooltipText(const gfx::Point& p) const override;
 
   AppListViewDelegate* const view_delegate_;           // Owned by AppListView.
 

ash/app_list/views/top_icon_animation_view.cc

@@ -18,7 +18,7 @@ namespace ash {
 
 TopIconAnimationView::TopIconAnimationView(AppsGridView* grid,
                                            const gfx::ImageSkia& icon,
-                                           const base::string16& title,
+                                           const std::u16string& title,
                                            const gfx::Rect& scaled_rect,
                                            bool open_folder,
                                            bool item_in_folder_icon)

ash/app_list/views/top_icon_animation_view.h

@@ -45,7 +45,7 @@ class TopIconAnimationView : public views::View,
   // The view will be self-cleaned by the end of animation.
   TopIconAnimationView(AppsGridView* grid,
                        const gfx::ImageSkia& icon,
-                       const base::string16& title,
+                       const std::u16string& title,
                        const gfx::Rect& scaled_rect,
                        bool open_folder,
                        bool item_in_folder_icon);

ash/app_menu/notification_item_view.cc

@@ -47,8 +47,8 @@ constexpr SkColor kNotificationTitleTextColor =
 NotificationItemView::NotificationItemView(
     NotificationMenuView::Delegate* delegate,
     views::SlideOutControllerDelegate* slide_out_controller_delegate,
-    const base::string16& title,
-    const base::string16& message,
+    const std::u16string& title,
+    const std::u16string& message,
     const gfx::Image& icon,
     const std::string& notification_id)
     : delegate_(delegate),
@@ -95,8 +95,8 @@ NotificationItemView::NotificationItemView(
 
 NotificationItemView::~NotificationItemView() = default;
 
-void NotificationItemView::UpdateContents(const base::string16& title,
-                                          const base::string16& message,
+void NotificationItemView::UpdateContents(const std::u16string& title,
+                                          const std::u16string& message,
                                           const gfx::Image& icon) {
   if (title_ != title) {
     title_ = title;

ash/app_menu/notification_item_view.h

@@ -36,16 +36,16 @@ class APP_MENU_EXPORT NotificationItemView : public views::View {
   NotificationItemView(
       NotificationMenuView::Delegate* delegate,
       views::SlideOutControllerDelegate* slide_out_controller_delegate,
-      const base::string16& title,
-      const base::string16& message,
+      const std::u16string& title,
+      const std::u16string& message,
       const gfx::Image& icon,
       const std::string& notification_id);
 
   ~NotificationItemView() override;
 
   // Updates the contents of the view.
-  void UpdateContents(const base::string16& title,
-                      const base::string16& message,
+  void UpdateContents(const std::u16string& title,
+                      const std::u16string& message,
                       const gfx::Image& icon);
 
   // views::View overrides:
@@ -57,8 +57,8 @@ class APP_MENU_EXPORT NotificationItemView : public views::View {
   void OnGestureEvent(ui::GestureEvent* event) override;
 
   const std::string& notification_id() const { return notification_id_; }
-  const base::string16& title() const { return title_; }
-  const base::string16& message() const { return message_; }
+  const std::u16string& title() const { return title_; }
+  const std::u16string& message() const { return message_; }
   const message_center::ProportionalImageView& proportional_image_view() const {
     return *proportional_icon_view_;
   }
@@ -83,8 +83,8 @@ class APP_MENU_EXPORT NotificationItemView : public views::View {
   std::unique_ptr<views::SlideOutController> slide_out_controller_;
 
   // Notification properties.
-  base::string16 title_;
-  base::string16 message_;
+  std::u16string title_;
+  std::u16string message_;
 
   // The identifier used by MessageCenter to identify this notification.
   const std::string notification_id_;

ash/app_menu/notification_menu_controller.cc

@@ -125,7 +125,7 @@ void NotificationMenuController::InitializeNotificationMenuView() {
   }
 
   app_menu_model_adapter_->model()->AddItem(NOTIFICATION_CONTAINER,
-                                            base::string16());
+                                            std::u16string());
   // Add the container MenuItemView to |root_menu_|.
   views::MenuItemView* container =
       root_menu_->AppendMenuItem(NOTIFICATION_CONTAINER);

ash/app_menu/notification_menu_header_view.cc

@@ -30,7 +30,7 @@ NotificationMenuHeaderView::NotificationMenuHeaderView() {
       kNotificationVerticalPadding, kNotificationHorizontalPadding)));
 
   notification_title_ = new views::Label(
-      base::string16(l10n_util::GetStringUTF16(
+      std::u16string(l10n_util::GetStringUTF16(
           IDS_MESSAGE_CENTER_NOTIFICATION_ACCESSIBLE_NAME_PLURAL)),
       {views::Label::GetDefaultFontList().DeriveWithSizeDelta(1)});
   notification_title_->SetEnabledColor(kNotificationHeaderTextColor);
@@ -38,7 +38,7 @@ NotificationMenuHeaderView::NotificationMenuHeaderView() {
   AddChildView(notification_title_);
 
   counter_ = new views::Label(
-      base::string16(),
+      std::u16string(),
       {views::Label::GetDefaultFontList().DeriveWithSizeDelta(1)});
   counter_->SetEnabledColor(kNotificationHeaderTextColor);
   counter_->SetLineHeight(kNotificationHeaderLineHeight);

ash/app_menu/notification_menu_view_test_api.cc

@@ -19,7 +19,7 @@ NotificationMenuViewTestAPI::NotificationMenuViewTestAPI(
 
 NotificationMenuViewTestAPI::~NotificationMenuViewTestAPI() = default;
 
-base::string16 NotificationMenuViewTestAPI::GetCounterViewContents() const {
+std::u16string NotificationMenuViewTestAPI::GetCounterViewContents() const {
   return notification_menu_view_->header_view_->counter_->GetText();
 }
 

ash/app_menu/notification_menu_view_test_api.h

@@ -23,7 +23,7 @@ class NotificationMenuViewTestAPI {
   ~NotificationMenuViewTestAPI();
 
   // Returns the numeric string contained in the counter view.
-  base::string16 GetCounterViewContents() const;
+  std::u16string GetCounterViewContents() const;
 
   // Returns the number of NotificationItemViews.
   int GetItemViewCount() const;

ash/app_menu/notification_menu_view_unittest.cc

@@ -119,8 +119,8 @@ class NotificationMenuViewTest : public views::ViewsTestBase {
 
   message_center::Notification AddNotification(
       const std::string& notification_id,
-      const base::string16& title,
-      const base::string16& message) {
+      const std::u16string& title,
+      const std::u16string& message) {
     const message_center::NotifierId notifier_id(
         message_center::NotifierType::APPLICATION, kTestAppId);
     message_center::Notification notification(
@@ -135,8 +135,8 @@ class NotificationMenuViewTest : public views::ViewsTestBase {
 
   message_center::Notification UpdateNotification(
       const std::string& notification_id,
-      const base::string16& title,
-      const base::string16& message) {
+      const std::u16string& title,
+      const std::u16string& message) {
     const message_center::NotifierId notifier_id(
         message_center::NotifierType::APPLICATION, kTestAppId);
     message_center::Notification notification(

ash/assistant/assistant_notification_controller_impl.cc

@@ -35,9 +35,9 @@ constexpr char kNotifierId[] = "assistant";
 std::unique_ptr<message_center::Notification> CreateSystemNotification(
     const message_center::NotifierId& notifier_id,
     const chromeos::assistant::AssistantNotification& notification) {
-  const base::string16 title = base::UTF8ToUTF16(notification.title);
-  const base::string16 message = base::UTF8ToUTF16(notification.message);
-  const base::string16 display_source =
+  const std::u16string title = base::UTF8ToUTF16(notification.title);
+  const std::u16string message = base::UTF8ToUTF16(notification.message);
+  const std::u16string display_source =
       l10n_util::GetStringUTF16(IDS_ASH_ASSISTANT_NOTIFICATION_DISPLAY_SOURCE);
 
   message_center::RichNotificationData data;
@@ -174,7 +174,7 @@ void AssistantNotificationControllerImpl::OnAllNotificationsRemoved(
 void AssistantNotificationControllerImpl::OnNotificationClicked(
     const std::string& id,
     const base::Optional<int>& button_index,
-    const base::Optional<base::string16>& reply) {
+    const base::Optional<std::u16string>& reply) {
   const AssistantNotification* notification = model_.GetNotificationById(id);
   if (!notification)
     return;

ash/assistant/assistant_notification_controller_impl.h

@@ -60,7 +60,7 @@ class ASH_EXPORT AssistantNotificationControllerImpl
   void OnNotificationClicked(
       const std::string& id,
       const base::Optional<int>& button_index,
-      const base::Optional<base::string16>& reply) override;
+      const base::Optional<std::u16string>& reply) override;
   void OnNotificationUpdated(const std::string& notification) override {}
   void OnNotificationRemoved(const std::string& notification_id,
                              bool by_user) override;

ash/assistant/ui/main_stage/assistant_onboarding_suggestion_view.cc

@@ -117,7 +117,7 @@ const gfx::ImageSkia& AssistantOnboardingSuggestionView::GetIcon() const {
   return icon_->GetImage();
 }
 
-const base::string16& AssistantOnboardingSuggestionView::GetText() const {
+const std::u16string& AssistantOnboardingSuggestionView::GetText() const {
   return label_->GetText();
 }
 

ash/assistant/ui/main_stage/assistant_onboarding_suggestion_view.h

@@ -52,7 +52,7 @@ class COMPONENT_EXPORT(ASSISTANT_UI) AssistantOnboardingSuggestionView
   const gfx::ImageSkia& GetIcon() const;
 
   // Returns the text for the suggestion.
-  const base::string16& GetText() const;
+  const std::u16string& GetText() const;
 
  private:
   void InitLayout(const chromeos::assistant::AssistantSuggestion& suggestion);

ash/assistant/ui/main_stage/assistant_opt_in_view.cc

@@ -39,7 +39,7 @@ views::StyledLabel::RangeStyleInfo CreateStyleInfo(
   return style;
 }
 
-base::string16 GetAction(int consent_status) {
+std::u16string GetAction(int consent_status) {
   return consent_status ==
                  chromeos::assistant::prefs::ConsentStatus::kUnauthorized
              ? l10n_util::GetStringUTF16(
@@ -154,11 +154,11 @@ void AssistantOptInView::InitLayout() {
 
 void AssistantOptInView::UpdateLabel(int consent_status) {
   // First substitution string: "Unlock more Assistant features."
-  const base::string16 unlock_features =
+  const std::u16string unlock_features =
       l10n_util::GetStringUTF16(IDS_ASH_ASSISTANT_OPT_IN_UNLOCK_MORE_FEATURES);
 
   // Second substitution string specifies the action to be taken.
-  const base::string16 action = GetAction(consent_status);
+  const std::u16string action = GetAction(consent_status);
 
   // Set the text, having replaced placeholders in the opt in prompt with
   // substitution strings and caching their offset positions for styling.

ash/assistant/ui/main_stage/assistant_query_view.cc

@@ -115,12 +115,12 @@ void AssistantQueryView::SetText(const std::string& high_confidence_text,
   // When coming from the server, both |high_confidence_text| and
   // |low_confidence_text| may be HTML escaped, so we need to unescape both
   // before displaying to avoid printing HTML entities to the user.
-  const base::string16& high_confidence_text_16 =
+  const std::u16string& high_confidence_text_16 =
       net::UnescapeForHTML(base::UTF8ToUTF16(high_confidence_text));
 
   high_confidence_label_->SetText(high_confidence_text_16);
 
-  const base::string16& low_confidence_text_16 =
+  const std::u16string& low_confidence_text_16 =
       net::UnescapeForHTML(base::UTF8ToUTF16(low_confidence_text));
 
   low_confidence_label_->SetText(low_confidence_text_16);

ash/assistant/ui/main_stage/suggestion_chip_view.cc

@@ -72,7 +72,7 @@ void SuggestionChipView::ChildVisibilityChanged(views::View* child) {
 }
 
 void SuggestionChipView::InitLayout(const AssistantSuggestion& suggestion) {
-  const base::string16 text = base::UTF8ToUTF16(suggestion.text);
+  const std::u16string text = base::UTF8ToUTF16(suggestion.text);
 
   // Accessibility.
   SetAccessibleName(text);
@@ -174,11 +174,11 @@ const gfx::ImageSkia& SuggestionChipView::GetIcon() const {
   return icon_view_->GetImage();
 }
 
-void SuggestionChipView::SetText(const base::string16& text) {
+void SuggestionChipView::SetText(const std::u16string& text) {
   text_view_->SetText(text);
 }
 
-const base::string16& SuggestionChipView::GetText() const {
+const std::u16string& SuggestionChipView::GetText() const {
   return text_view_->GetText();
 }
 

ash/assistant/ui/main_stage/suggestion_chip_view.h

@@ -46,8 +46,8 @@ class COMPONENT_EXPORT(ASSISTANT_UI) SuggestionChipView : public views::Button {
   void SetIcon(const gfx::ImageSkia& icon);
   const gfx::ImageSkia& GetIcon() const;
 
-  void SetText(const base::string16& text);
-  const base::string16& GetText() const;
+  void SetText(const std::u16string& text);
+  const std::u16string& GetText() const;
 
   const base::UnguessableToken& suggestion_id() const { return suggestion_id_; }
 

ash/capture_mode/capture_label_view.cc

@@ -153,7 +153,7 @@ CaptureLabelView::CaptureLabelView(CaptureModeSession* capture_mode_session)
   label_button_ = AddChildView(std::make_unique<views::LabelButton>(
       base::BindRepeating(&CaptureLabelView::OnButtonPressed,
                           base::Unretained(this)),
-      base::string16()));
+      std::u16string()));
   label_button_->SetPaintToLayer();
   label_button_->layer()->SetFillsBoundsOpaquely(false);
   label_button_->SetEnabledTextColors(text_color);
@@ -167,7 +167,7 @@ CaptureLabelView::CaptureLabelView(CaptureModeSession* capture_mode_session)
   label_button_->SetInkDropBaseColor(ripple_attributes.base_color);
   label_button_->SetFocusBehavior(views::View::FocusBehavior::ACCESSIBLE_ONLY);
 
-  label_ = AddChildView(std::make_unique<views::Label>(base::string16()));
+  label_ = AddChildView(std::make_unique<views::Label>(std::u16string()));
   label_->SetPaintToLayer();
   label_->layer()->SetFillsBoundsOpaquely(false);
   label_->SetEnabledColor(text_color);
@@ -188,7 +188,7 @@ void CaptureLabelView::UpdateIconAndText() {
       AshColorProvider::ContentLayerType::kIconColorPrimary);
 
   gfx::ImageSkia icon;
-  base::string16 text;
+  std::u16string text;
   switch (source) {
     case CaptureModeSource::kFullscreen:
       text = l10n_util::GetStringUTF16(

ash/capture_mode/capture_mode_toggle_button.cc

@@ -53,7 +53,7 @@ void CaptureModeToggleButton::OnPaintBackground(gfx::Canvas* canvas) {
 
 void CaptureModeToggleButton::GetAccessibleNodeData(ui::AXNodeData* node_data) {
   ImageButton::GetAccessibleNodeData(node_data);
-  const base::string16 tooltip = GetTooltipText(gfx::Point());
+  const std::u16string tooltip = GetTooltipText(gfx::Point());
   DCHECK(!tooltip.empty());
   node_data->SetName(tooltip);
   node_data->role = ax::mojom::Role::kToggleButton;

ash/capture_mode/stop_recording_button_tray.cc

@@ -47,7 +47,7 @@ bool StopRecordingButtonTray::PerformAction(const ui::Event& event) {
   return true;
 }
 
-base::string16 StopRecordingButtonTray::GetAccessibleNameForTray() {
+std::u16string StopRecordingButtonTray::GetAccessibleNameForTray() {
   return l10n_util::GetStringUTF16(
       IDS_ASH_STATUS_AREA_STOP_RECORDING_BUTTON_ACCESSIBLE_NAME);
 }

ash/capture_mode/stop_recording_button_tray.h

@@ -22,7 +22,7 @@ class StopRecordingButtonTray : public TrayBackgroundView {
   // TrayBackgroundView:
   bool PerformAction(const ui::Event& event) override;
   void ClickedOutsideBubble() override {}
-  base::string16 GetAccessibleNameForTray() override;
+  std::u16string GetAccessibleNameForTray() override;
   void HandleLocaleChange() override {}
   void HideBubbleWithView(const TrayBubbleView* bubble_view) override {}
 };

ash/child_accounts/parent_access_controller_impl.cc

@@ -24,7 +24,7 @@ namespace {
 // Number of digits displayed in parent access code input.
 constexpr int kParentAccessCodePinLength = 6;
 
-base::string16 GetTitle(SupervisedAction action) {
+std::u16string GetTitle(SupervisedAction action) {
   int title_id;
   switch (action) {
     case SupervisedAction::kUnlockTimeLimits:
@@ -44,7 +44,7 @@ base::string16 GetTitle(SupervisedAction action) {
   return l10n_util::GetStringUTF16(title_id);
 }
 
-base::string16 GetDescription(SupervisedAction action) {
+std::u16string GetDescription(SupervisedAction action) {
   int description_id;
   switch (action) {
     case SupervisedAction::kUnlockTimeLimits:
@@ -64,7 +64,7 @@ base::string16 GetDescription(SupervisedAction action) {
   return l10n_util::GetStringUTF16(description_id);
 }
 
-base::string16 GetAccessibleTitle() {
+std::u16string GetAccessibleTitle() {
   return l10n_util::GetStringUTF16(IDS_ASH_LOGIN_PARENT_ACCESS_DIALOG_NAME);
 }
 

ash/clipboard/clipboard_history_menu_model_adapter.cc

@@ -89,7 +89,7 @@ void ClipboardHistoryMenuModelAdapter::Run(
   const ui::DataTransferEndpoint data_dst(ui::EndpointType::kDefault,
                                           /*notify_if_restricted=*/false);
   for (const auto& item : items) {
-    model_->AddItem(command_id, base::string16());
+    model_->AddItem(command_id, std::u16string());
     item_snapshots_.emplace(command_id, item);
     ++command_id;
   }

ash/clipboard/clipboard_history_resource_manager.cc

@@ -86,21 +86,21 @@ class UnrenderedHTMLPlaceholderImage : public gfx::CanvasImageSource {
 // Helpers ---------------------------------------------------------------------
 
 // Returns the localized string for the specified |resource_id|.
-base::string16 GetLocalizedString(int resource_id) {
+std::u16string GetLocalizedString(int resource_id) {
   return ui::ResourceBundle::GetSharedInstance().GetLocalizedString(
       resource_id);
 }
 
 // Returns the label to display for the custom data contained within |data|.
-base::string16 GetLabelForCustomData(const ui::ClipboardData& data) {
+std::u16string GetLabelForCustomData(const ui::ClipboardData& data) {
   // Currently the only supported type of custom data is file system data. This
   // code should not be reached if `data` does not contain file system data.
-  base::string16 sources;
+  std::u16string sources;
   std::vector<base::StringPiece16> source_list;
   ClipboardHistoryUtil::GetSplitFileSystemData(data, &source_list, &sources);
   if (sources.empty()) {
     NOTREACHED();
-    return base::string16();
+    return std::u16string();
   }
 
   // Strip path information, so all that's left are file names.
@@ -149,7 +149,7 @@ ui::ImageModel ClipboardHistoryResourceManager::GetImageModel(
   return cached_image_model->image_model;
 }
 
-base::string16 ClipboardHistoryResourceManager::GetLabel(
+std::u16string ClipboardHistoryResourceManager::GetLabel(
     const ClipboardHistoryItem& item) const {
   const ui::ClipboardData& data = item.data();
   switch (ClipboardHistoryUtil::CalculateMainFormat(data).value()) {