Use std::string_view in PrefRegistry.

Bug: 349741884
Change-Id: I495cc538641abe57a93b586d467d9d0049c23b67
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5678719
Reviewed-by: Dominic Battré <battre@chromium.org>
Commit-Queue: Dominic Battré <battre@chromium.org>
Auto-Submit: Jan Keitel <jkeitel@google.com>
Cr-Commit-Position: refs/heads/main@{#1326193}

components/prefs/default_pref_store.cc

@@ -4,7 +4,6 @@
 
 #include "components/prefs/default_pref_store.h"
 
-#include <string>
 #include <string_view>
 #include <utility>
 
@@ -41,8 +40,7 @@ void DefaultPrefStore::SetDefaultValue(std::string_view key, Value value) {
   prefs_.SetValue(key, std::move(value));
 }
 
-void DefaultPrefStore::ReplaceDefaultValue(const std::string& key,
-                                           Value value) {
+void DefaultPrefStore::ReplaceDefaultValue(std::string_view key, Value value) {
   DCHECK(GetValue(key, nullptr));
   bool notify = prefs_.SetValue(key, std::move(value));
   if (notify) {

components/prefs/default_pref_store.h

@@ -6,7 +6,6 @@
 #define COMPONENTS_PREFS_DEFAULT_PREF_STORE_H_
 
 #include <memory>
-#include <string>
 #include <string_view>
 
 #include "base/observer_list.h"
@@ -39,7 +38,7 @@ class COMPONENTS_PREFS_EXPORT DefaultPrefStore : public PrefStore {
 
   // Replaces the the value for `key` with a new value. Should only be called
   // if a value has already been set; otherwise call SetDefaultValue().
-  void ReplaceDefaultValue(const std::string& key, base::Value value);
+  void ReplaceDefaultValue(std::string_view key, base::Value value);
 
   const_iterator begin() const;
   const_iterator end() const;

components/prefs/pref_registry.cc

@@ -21,8 +21,7 @@ PrefRegistry::PrefRegistry()
 PrefRegistry::~PrefRegistry() {
 }
 
-uint32_t PrefRegistry::GetRegistrationFlags(
-    const std::string& pref_name) const {
+uint32_t PrefRegistry::GetRegistrationFlags(std::string_view pref_name) const {
   const auto& it = registration_flags_.find(pref_name);
   return it != registration_flags_.end() ? it->second : NO_REGISTRATION_FLAGS;
 }
@@ -39,7 +38,7 @@ PrefRegistry::const_iterator PrefRegistry::end() const {
   return defaults_->end();
 }
 
-void PrefRegistry::SetDefaultPrefValue(const std::string& pref_name,
+void PrefRegistry::SetDefaultPrefValue(std::string_view pref_name,
                                        base::Value value) {
   const base::Value* current_value = nullptr;
   DCHECK(defaults_->GetValue(pref_name, &current_value))

components/prefs/pref_registry.h

@@ -14,6 +14,7 @@
 #include "base/memory/ref_counted.h"
 #include "components/prefs/pref_value_map.h"
 #include "components/prefs/prefs_export.h"
+#include "components/prefs/transparent_unordered_string_map.h"
 
 namespace base {
 class Value;
@@ -52,8 +53,8 @@ class COMPONENTS_PREFS_EXPORT PrefRegistry
   // Registering a pref as public allows other services to access it.
   static constexpr PrefRegistrationFlags PUBLIC = 1 << 9;
 
-  typedef PrefValueMap::const_iterator const_iterator;
-  typedef std::unordered_map<std::string, uint32_t> PrefRegistrationFlagsMap;
+  using const_iterator = PrefValueMap::const_iterator;
+  using PrefRegistrationFlagsMap = TransparentUnorderedStringMap<uint32_t>;
 
   PrefRegistry();
 
@@ -62,7 +63,7 @@ class COMPONENTS_PREFS_EXPORT PrefRegistry
 
   // Retrieve the set of registration flags for the given preference. The return
   // value is a bitmask of PrefRegistrationFlags.
-  uint32_t GetRegistrationFlags(const std::string& pref_name) const;
+  uint32_t GetRegistrationFlags(std::string_view pref_name) const;
 
   // Gets the registered defaults.
   scoped_refptr<PrefStore> defaults();
@@ -74,7 +75,7 @@ class COMPONENTS_PREFS_EXPORT PrefRegistry
   // Changes the default value for a preference.
   //
   // `pref_name` must be a previously registered preference.
-  void SetDefaultPrefValue(const std::string& pref_name, base::Value value);
+  void SetDefaultPrefValue(std::string_view pref_name, base::Value value);
 
  protected:
   friend class base::RefCounted<PrefRegistry>;

components/prefs/pref_service.cc

@@ -383,14 +383,14 @@ const base::Value* PrefService::GetUserPrefValue(std::string_view path) const {
   return value;
 }
 
-void PrefService::SetDefaultPrefValue(const std::string& path,
+void PrefService::SetDefaultPrefValue(std::string_view path,
                                       base::Value value) {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   pref_registry_->SetDefaultPrefValue(path, std::move(value));
 }
 
 const base::Value* PrefService::GetDefaultPrefValue(
-    const std::string& path) const {
+    std::string_view path) const {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
   // Lookup the preference in the default store.
   const base::Value* value = nullptr;

components/prefs/pref_service.h

@@ -325,12 +325,12 @@ class COMPONENTS_PREFS_EXPORT PrefService {
   //
   // Will cause a pref change notification to be fired if this causes
   // the effective value to change.
-  void SetDefaultPrefValue(const std::string& path, base::Value value);
+  void SetDefaultPrefValue(std::string_view path, base::Value value);
 
   // Returns the default value of the given preference. |path| must point to a
   // registered preference. In that case, will never return nullptr, so callers
   // do not need to check this.
-  const base::Value* GetDefaultPrefValue(const std::string& path) const;
+  const base::Value* GetDefaultPrefValue(std::string_view path) const;
 
   // Returns true if a value has been set for the specified path.
   // NOTE: this is NOT the same as FindPreference. In particular