Add callback list to PrefModelAssociator after sync data is loaded

components/syncable_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 COMPONENTS_SYNCABLE_PREFS_PREF_SERVICE_SYNCABLE_H_
 #define COMPONENTS_SYNCABLE_PREFS_PREF_SERVICE_SYNCABLE_H_
 
 #include <stdint.h>
 
 #include <vector>
@@ skipping 55 matching lines @@
   // priority preferences.
   bool IsPrioritySyncing();
 
   // Returns true if the pref under the given name is pulled down from sync.
   // Note this does not refer to SYNCABLE_PREF.
   bool IsPrefSynced(const std::string& name) const;
 
   void AddObserver(PrefServiceSyncableObserver* observer);
   void RemoveObserver(PrefServiceSyncableObserver* observer);
 
+  void RegisterMergeDataFinishedCallback(const base::Closure& callback);
+
   // 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.
   void UpdateCommandLinePrefStore(PrefStore* cmd_line_store) override;
 
   void AddSyncedPrefObserver(const std::string& name,
                              SyncedPrefObserver* observer);
   void RemoveSyncedPrefObserver(const std::string& name,
@@ skipping 24 matching lines @@
   PrefModelAssociator priority_pref_sync_associator_;
 
   base::ObserverList<PrefServiceSyncableObserver> observer_list_;
 
   DISALLOW_COPY_AND_ASSIGN(PrefServiceSyncable);
 };
 
 }  // namespace syncable_prefs
 
 #endif  // COMPONENTS_SYNCABLE_PREFS_PREF_SERVICE_SYNCABLE_H_