Add histograms to track synced pref changes.

chrome/browser/prefs/pref_service_syncable.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_PREFS_PREF_SERVICE_SYNCABLE_H_
 #define CHROME_BROWSER_PREFS_PREF_SERVICE_SYNCABLE_H_
 
 #include "base/prefs/pref_service.h"
 #include "chrome/browser/prefs/pref_model_associator.h"
+#include "chrome/browser/prefs/synced_pref_observer.h"
 #include "components/user_prefs/pref_registry_syncable.h"
 
 class PrefServiceSyncableObserver;
 class Profile;
 
 namespace syncer {
 class SyncableService;
 }
 
 // A PrefService that can be synced. Users are forced to declare
@@ skipping 53 matching lines @@
   void AddObserver(PrefServiceSyncableObserver* observer);
   void RemoveObserver(PrefServiceSyncableObserver* observer);
 
   // TODO(zea): Have PrefServiceSyncable implement
   // syncer::SyncableService directly.
   syncer::SyncableService* GetSyncableService(const syncer::ModelType& type);
 
   // Do not call this after having derived an incognito or per tab pref service.
   virtual void UpdateCommandLinePrefStore(PrefStore* cmd_line_store) OVERRIDE;
 
+  void AddSyncedPrefObserver(const std::string& name,
+                             SyncedPrefObserver* observer);
+  void RemoveSyncedPrefObserver(const std::string& name,
+                                SyncedPrefObserver* observer);
+
  private:
   friend class PrefModelAssociator;
 
   void AddRegisteredSyncablePreference(
       const char* path,
       const user_prefs::PrefRegistrySyncable::PrefSyncStatus sync_status);
 
   // Invoked internally when the IsSyncing() state changes.
   void OnIsSyncingChanged();
 
   // Process a local preference change. This can trigger new SyncChanges being
   // sent to the syncer.
   void ProcessPrefChange(const std::string& name);
 
   // Whether CreateIncognitoPrefService() has been called to create a
   // "forked" PrefService.
   bool pref_service_forked_;
 
   PrefModelAssociator pref_sync_associator_;
   PrefModelAssociator priority_pref_sync_associator_;
 
   ObserverList<PrefServiceSyncableObserver> observer_list_;
 
   DISALLOW_COPY_AND_ASSIGN(PrefServiceSyncable);
 };
 
 #endif  // CHROME_BROWSER_PREFS_PREF_SERVICE_SYNCABLE_H_