[ios blink] Adjust process initialization

Enable initialization of the feature list before mojo
is initialized. This changes the creation of the
ApplicationContextImpl to happen in a PostEarlyInitialization
callback in the IOSMainDelegate.

Bug: 40261735
Change-Id: If2b76a2fad420fb15551354ecb65a85310777504
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6293264
Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Commit-Queue: Dave Tapuska <dtapuska@chromium.org>
Reviewed-by: Justin Cohen <justincohen@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1424792}

ios/chrome/browser/application_context/model/application_context_impl.mm

@@ -457,11 +457,15 @@ ApplicationContextImpl::GetNetworkConnectionTracker() {
 BrowserPolicyConnectorIOS* ApplicationContextImpl::GetBrowserPolicyConnector() {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   if (!browser_policy_connector_.get()) {
+#if !BUILDFLAG(USE_BLINK)
     // Ensure that the ResourceBundle has already been initialized. If this
     // DCHECK ever fails, a call to
     // BrowserPolicyConnector::OnResourceBundleCreated() will need to be added
     // later in the startup sequence, after the ResourceBundle is initialized.
+    // Blink based startup will call OnResourceBundleCreated in
+    // IOSChromeMainParts::PreCreateThreads.
     DCHECK(ui::ResourceBundle::HasSharedInstance());
+#endif
     version_info::Channel channel = ::GetChannel();
     policy::ConfigurationPolicyProvider* test_policy_provider =
         tests_hook::GetOverriddenPlatformPolicyProvider();

ios/chrome/browser/policy/model/browser_policy_connector_ios.h

@@ -79,6 +79,8 @@ class BrowserPolicyConnectorIOS : public policy::BrowserPolicyConnector {
   // line switch anyway.
   bool IsCommandLineSwitchSupported() const override;
 
+  void OnResourceBundleCreated();
+
  protected:
   // BrowserPolicyConnectorBase.
   std::vector<std::unique_ptr<policy::ConfigurationPolicyProvider>>

ios/chrome/browser/policy/model/browser_policy_connector_ios.mm

@@ -165,3 +165,7 @@ BrowserPolicyConnectorIOS::CreatePlatformProvider() {
   return std::make_unique<AsyncPolicyProvider>(GetSchemaRegistry(),
                                                std::move(loader));
 }
+
+void BrowserPolicyConnectorIOS::OnResourceBundleCreated() {
+  BrowserPolicyConnectorBase::OnResourceBundleCreated();
+}

ios/chrome/browser/web/model/chrome_main_parts.h

@@ -27,6 +27,10 @@ class IOSChromeMainParts : public web::WebMainParts {
 
   ~IOSChromeMainParts() override;
 
+  // Initializes the field trials and feature list. This should be called early
+  // before features such as mojo are initialized.
+  void InitializeFieldTrialAndFeatureList();
+
  private:
   // web::WebMainParts implementation.
   void PreCreateMainMessageLoop() override;
@@ -47,6 +51,12 @@ class IOSChromeMainParts : public web::WebMainParts {
   // Constructs the metrics service and initializes metrics recording.
   void SetupMetrics();
 
+  // Create the application context.
+  void CreateApplicationContext();
+
+  // Apply the command line to the feature list.
+  void ApplyFeatureList();
+
   // Starts recording of metrics. This can only be called after we have a file
   // thread.
   void StartMetricsRecording();

ios/chrome/browser/web/model/chrome_main_parts.mm

@@ -136,7 +136,9 @@ IOSChromeMainParts::~IOSChromeMainParts() {
 }
 
 void IOSChromeMainParts::PreCreateMainMessageLoop() {
+#if !BUILDFLAG(USE_BLINK)
   l10n_util::OverrideLocaleWithCocoaLocale();
+#endif
   const std::string loaded_locale =
       ui::ResourceBundle::InitSharedInstanceWithLocale(
           std::string(), nullptr, ui::ResourceBundle::LOAD_COMMON_RESOURCES);
@@ -152,22 +154,15 @@ void IOSChromeMainParts::PreCreateMainMessageLoop() {
       resources_pack_path, ui::k100Percent);
 }
 
-void IOSChromeMainParts::PreCreateThreads() {
-  // Create and start the stack sampling profiler if CANARY or DEV. The warning
-  // below doesn't apply.
-  const version_info::Channel channel = ::GetChannel();
-  if (channel == version_info::Channel::CANARY ||
-      channel == version_info::Channel::DEV) {
-    sampling_profiler_ = IOSThreadProfiler::CreateAndStartOnMainThread();
-    IOSThreadProfiler::SetMainThreadTaskRunner(
-        base::SingleThreadTaskRunner::GetCurrentDefault());
-  }
-
-  // IMPORTANT
-  // Calls in this function should not post tasks or create threads as
-  // components used to handle those tasks are not yet available. This work
-  // should be deferred to PreMainMessageLoopRunImpl.
+void IOSChromeMainParts::InitializeFieldTrialAndFeatureList() {
+#if BUILDFLAG(USE_BLINK)
+  l10n_util::OverrideLocaleWithCocoaLocale();
+  CreateApplicationContext();
+  ApplyFeatureList();
+#endif
+}
 
+void IOSChromeMainParts::CreateApplicationContext() {
   // The initial read is done synchronously, the TaskPriority is thus only used
   // for flushes to disks and BACKGROUND is therefore appropriate. Priority of
   // remaining BACKGROUND+BLOCK_SHUTDOWN tasks is bumped by the ThreadPool on
@@ -178,36 +173,15 @@ void IOSChromeMainParts::PreCreateThreads() {
            base::TaskShutdownBehavior::BLOCK_SHUTDOWN},
           base::SingleThreadTaskRunnerThreadMode::DEDICATED);
 
-  base::FilePath local_state_path;
-  CHECK(base::PathService::Get(ios::FILE_LOCAL_STATE, &local_state_path));
   application_context_.reset(new ApplicationContextImpl(
       local_state_task_runner.get(), *parsed_command_line_,
       l10n_util::GetLocaleOverride(),
       base::SysNSStringToUTF8(
           [[NSLocale currentLocale] objectForKey:NSLocaleCountryCode])));
   DCHECK_EQ(application_context_.get(), GetApplicationContext());
+}
 
-  // Check the first run state early; this must be done before IO is disallowed
-  // so that later calls can use the cached value.
-  static crash_reporter::CrashKeyString<4> key("first-run");
-  if (FirstRun::IsChromeFirstRun()) {
-    key.Set("yes");
-  }
-
-  // Compute device restore flag before IO is disallowed on UI thread, so the
-  // value is available from cache synchronously.
-  static crash_reporter::CrashKeyString<8> device_restore_key("device-restore");
-  switch (IsFirstSessionAfterDeviceRestore()) {
-    case signin::Tribool::kTrue:
-      device_restore_key.Set("yes");
-      break;
-    case signin::Tribool::kFalse:
-      break;
-    case signin::Tribool::kUnknown:
-      device_restore_key.Set("unknown");
-      break;
-  }
-
+void IOSChromeMainParts::ApplyFeatureList() {
   base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
 
   // Convert freeform experimental settings into switches before initializing
@@ -245,6 +219,55 @@ void IOSChromeMainParts::PreCreateThreads() {
   // emitting profiler metadata since the profiler doesn't run on iOS.
   base::features::Init(
       base::features::EmitThreadControllerProfilerMetadata::kFeatureDependent);
+}
+
+void IOSChromeMainParts::PreCreateThreads() {
+  // Create and start the stack sampling profiler if CANARY or DEV. The warning
+  // below doesn't apply.
+  const version_info::Channel channel = ::GetChannel();
+  if (channel == version_info::Channel::CANARY ||
+      channel == version_info::Channel::DEV) {
+    sampling_profiler_ = IOSThreadProfiler::CreateAndStartOnMainThread();
+    IOSThreadProfiler::SetMainThreadTaskRunner(
+        base::SingleThreadTaskRunner::GetCurrentDefault());
+  }
+
+#if BUILDFLAG(USE_BLINK)
+  GetApplicationContext()
+      ->GetBrowserPolicyConnector()
+      ->OnResourceBundleCreated();
+#else
+  // IMPORTANT
+  // Calls in this function should not post tasks or create threads as
+  // components used to handle those tasks are not yet available. This work
+  // should be deferred to PreMainMessageLoopRunImpl.
+  CreateApplicationContext();
+#endif
+
+  // Check the first run state early; this must be done before IO is disallowed
+  // so that later calls can use the cached value.
+  static crash_reporter::CrashKeyString<4> key("first-run");
+  if (FirstRun::IsChromeFirstRun()) {
+    key.Set("yes");
+  }
+
+  // Compute device restore flag before IO is disallowed on UI thread, so the
+  // value is available from cache synchronously.
+  static crash_reporter::CrashKeyString<8> device_restore_key("device-restore");
+  switch (IsFirstSessionAfterDeviceRestore()) {
+    case signin::Tribool::kTrue:
+      device_restore_key.Set("yes");
+      break;
+    case signin::Tribool::kFalse:
+      break;
+    case signin::Tribool::kUnknown:
+      device_restore_key.Set("unknown");
+      break;
+  }
+
+#if !BUILDFLAG(USE_BLINK)
+  ApplyFeatureList();
+#endif
 
   // Set metrics upload for stack/heap profiles.
   IOSThreadProfiler::SetBrowserProcessReceiverCallback(base::BindRepeating(
@@ -278,6 +301,9 @@ void IOSChromeMainParts::PreCreateThreads() {
       @"RemoveProtectionFromPrefKey";
   if ([NSUserDefaults.standardUserDefaults
           boolForKey:kRemoveProtectionFromPrefFileKey]) {
+    base::FilePath local_state_path;
+    CHECK(base::PathService::Get(ios::FILE_LOCAL_STATE, &local_state_path));
+
     // Restore default protection level when user is no longer in the
     // experimental group.
     SetProtectionLevel(local_state_path,
@@ -391,9 +417,9 @@ void IOSChromeMainParts::SetUpFieldTrials(
     const std::string& command_line_variation_ids) {
   base::SetRecordActionTaskRunner(web::GetUIThreadTaskRunner({}));
 
-  // FeatureList requires VariationsIdsProvider to be created.
+// This will occur inside //content for blink.
 #if !BUILDFLAG(USE_BLINK)
-  // TODO(crbug.com/40261735) Move variations to PostEarlyInitialization.
+  // FeatureList requires VariationsIdsProvider to be created.
   variations::VariationsIdsProvider::Create(
       variations::VariationsIdsProvider::Mode::kUseSignedInState);
 #endif
@@ -416,14 +442,11 @@ void IOSChromeMainParts::SetUpFieldTrials(
       application_context_->GetAdditionalFeaturesController();
   additional_features_controller->RegisterFeatureList(feature_list.get());
 
-#if !BUILDFLAG(USE_BLINK)
-  // TODO(crbug.com/40261735) Move variations to PostEarlyInitialization.
   application_context_->GetVariationsService()->SetUpFieldTrials(
       variation_ids, command_line_variation_ids,
       std::vector<base::FeatureList::FeatureOverrideInfo>(),
       std::move(feature_list), &ios_field_trials_);
   additional_features_controller->FeatureListDidCompleteSetup();
-#endif
 }
 
 void IOSChromeMainParts::SetupMetrics() {

ios/chrome/browser/web/model/chrome_web_client.h

@@ -10,8 +10,11 @@
 #include <string_view>
 #include <vector>
 
+#include "build/blink_buildflags.h"
 #import "ios/web/public/web_client.h"
 
+class IOSChromeMainParts;
+
 // Chrome implementation of WebClient.
 class ChromeWebClient : public web::WebClient {
  public:
@@ -24,6 +27,7 @@ class ChromeWebClient : public web::WebClient {
 
   // WebClient implementation.
   std::unique_ptr<web::WebMainParts> CreateWebMainParts() override;
+  void InitializeFieldTrialAndFeatureList() override;
   void PreWebViewCreation() const override;
   void AddAdditionalSchemes(Schemes* schemes) const override;
   std::string GetApplicationLocale() const override;
@@ -71,6 +75,10 @@ class ChromeWebClient : public web::WebClient {
  private:
   // Reference to a view that is attached to a window.
   UIView* windowed_container_ = nil;
+
+#if BUILDFLAG(USE_BLINK)
+  std::unique_ptr<IOSChromeMainParts> main_parts_;
+#endif
 };
 
 #endif  // IOS_CHROME_BROWSER_WEB_MODEL_CHROME_WEB_CLIENT_H_

ios/chrome/browser/web/model/chrome_web_client.mm

@@ -254,8 +254,21 @@ ChromeWebClient::ChromeWebClient() {}
 ChromeWebClient::~ChromeWebClient() {}
 
 std::unique_ptr<web::WebMainParts> ChromeWebClient::CreateWebMainParts() {
+#if BUILDFLAG(USE_BLINK)
+  CHECK(main_parts_);
+  return std::move(main_parts_);
+#else
   return std::make_unique<IOSChromeMainParts>(
       *base::CommandLine::ForCurrentProcess());
+#endif
+}
+
+void ChromeWebClient::InitializeFieldTrialAndFeatureList() {
+#if BUILDFLAG(USE_BLINK)
+  main_parts_ = std::make_unique<IOSChromeMainParts>(
+      *base::CommandLine::ForCurrentProcess());
+  main_parts_->InitializeFieldTrialAndFeatureList();
+#endif
 }
 
 void ChromeWebClient::PreWebViewCreation() const {}

ios/web/content/init/BUILD.gn

@@ -19,8 +19,8 @@ source_set("init") {
     "ios_content_browser_client.h",
     "ios_content_main_runner.cc",
     "ios_content_main_runner.h",
-    "ios_main_delegate.cc",
     "ios_main_delegate.h",
+    "ios_main_delegate.mm",
     "ios_renderer_main_delegate.cc",
     "ios_renderer_main_delegate.h",
   ]

ios/web/content/init/ios_main_delegate.h

@@ -33,6 +33,9 @@ class IOSMainDelegate : public content::ContentMainDelegate {
   content::ContentClient* CreateContentClient() override;
   content::ContentBrowserClient* CreateContentBrowserClient() override;
   content::ContentRendererClient* CreateContentRendererClient() override;
+  bool ShouldCreateFeatureList(InvokedIn invoked_in) override;
+  bool ShouldInitializeMojo(InvokedIn invoked_in) override;
+  std::optional<int> PostEarlyInitialization(InvokedIn invoked_in) override;
 
   absl::variant<int, content::MainFunctionParams> RunProcess(
       const std::string& process_type,

ios/web/content/init/ios_main_delegate.mm

@@ -2,18 +2,45 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "ios/web/content/init/ios_main_delegate.h"
+#import "ios/web/content/init/ios_main_delegate.h"
 
-#include "content/public/renderer/content_renderer_client.h"
-#include "ios/web/content/init/ios_content_browser_client.h"
-#include "ios/web/content/init/ios_content_client.h"
-#include "ios/web/content/init/ios_content_renderer_client.h"
+#import "content/public/app/initialize_mojo_core.h"
+#import "content/public/renderer/content_renderer_client.h"
+#import "ios/web/content/init/ios_content_browser_client.h"
+#import "ios/web/content/init/ios_content_client.h"
+#import "ios/web/content/init/ios_content_renderer_client.h"
+#import "ios/web/public/web_client.h"
 
 namespace web {
 
 IOSMainDelegate::IOSMainDelegate() {}
 IOSMainDelegate::~IOSMainDelegate() {}
 
+bool IOSMainDelegate::ShouldCreateFeatureList(InvokedIn invoked_in) {
+  // The //content layer is always responsible for creating the FeatureList in
+  // child processes.
+  if (absl::holds_alternative<InvokedInChildProcess>(invoked_in)) {
+    return true;
+  }
+
+  // Otherwise, normally the browser process in Chrome is responsible for
+  // creating the FeatureList.
+  return false;
+}
+
+bool IOSMainDelegate::ShouldInitializeMojo(InvokedIn invoked_in) {
+  return ShouldCreateFeatureList(invoked_in);
+}
+
+std::optional<int> IOSMainDelegate::PostEarlyInitialization(
+    InvokedIn invoked_in) {
+#if BUILDFLAG(USE_BLINK)
+  web::GetWebClient()->InitializeFieldTrialAndFeatureList();
+  content::InitializeMojoCore();
+#endif
+  return std::nullopt;
+}
+
 content::ContentClient* IOSMainDelegate::CreateContentClient() {
   content_client_ = std::make_unique<IOSContentClient>();
   return content_client_.get();

ios/web/public/web_client.h

@@ -59,6 +59,10 @@ class WebClient {
   // browser startup code.
   virtual std::unique_ptr<WebMainParts> CreateWebMainParts();
 
+  // Allows the embedder to initialize the field trial and features list
+  // early.
+  virtual void InitializeFieldTrialAndFeatureList() {}
+
   // Gives the embedder a chance to perform tasks before a web view is created.
   virtual void PreWebViewCreation() const {}