Leftover cleanups from https://codereview.chromium.org/324493002 .

Moves one more method from PersistentPrefStore to WritablePrefStore. This allows most "writing" operations to be possible without the more complex PersistentPrefStore API.

BUG=None

Review URL: https://codereview.chromium.org/389333003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@282967 0039d316-1c4b-4281-b951-d872f2087c98

base/prefs/persistent_pref_store.h

@@ -46,12 +46,6 @@ class BASE_PREFS_EXPORT PersistentPrefStore : public WriteablePrefStore {
     virtual void OnError(PrefReadError error) = 0;
   };
 
-  // Same as SetValue, but doesn't generate notifications. This is used by
-  // PrefService::GetMutableUserPref() in order to put empty entries
-  // into the user pref store. Using SetValue is not an option since existing
-  // tests rely on the number of notifications generated.
-  virtual void SetValueSilently(const std::string& key, base::Value* value) = 0;
-
   // Whether the store is in a pseudo-read-only mode where changes are not
   // actually persisted to disk.  This happens in some cases when there are
   // read errors during startup.

base/prefs/value_map_pref_store.cc

@@ -47,6 +47,11 @@ void ValueMapPrefStore::ReportValueChanged(const std::string& key) {
   FOR_EACH_OBSERVER(Observer, observers_, OnPrefValueChanged(key));
 }
 
+void ValueMapPrefStore::SetValueSilently(const std::string& key,
+                                         base::Value* value) {
+  prefs_.SetValue(key, value);
+}
+
 ValueMapPrefStore::~ValueMapPrefStore() {}
 
 void ValueMapPrefStore::NotifyInitializationCompleted() {

base/prefs/value_map_pref_store.h

@@ -33,6 +33,8 @@ class BASE_PREFS_EXPORT ValueMapPrefStore : public WriteablePrefStore {
   virtual bool GetMutableValue(const std::string& key,
                                base::Value** value) OVERRIDE;
   virtual void ReportValueChanged(const std::string& key) OVERRIDE;
+  virtual void SetValueSilently(const std::string& key,
+                                base::Value* value) OVERRIDE;
 
  protected:
   virtual ~ValueMapPrefStore();

base/prefs/writeable_pref_store.h

@@ -36,6 +36,11 @@ class BASE_PREFS_EXPORT WriteablePrefStore : public PrefStore {
   // ReportValueChanged will trigger notifications even if nothing has changed.
   virtual void ReportValueChanged(const std::string& key) = 0;
 
+  // Same as SetValue, but doesn't generate notifications. This is used by
+  // PrefService::GetMutableUserPref() in order to put empty entries
+  // into the user pref store. Using SetValue is not an option since existing
+  // tests rely on the number of notifications generated.
+  virtual void SetValueSilently(const std::string& key, base::Value* value) = 0;
 
  protected:
   virtual ~WriteablePrefStore() {}