Introduce PrefRegistrySyncable, simplifying PrefServiceSyncable.

chrome/browser/prefs/pref_model_associator.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_MODEL_ASSOCIATOR_H_
 #define CHROME_BROWSER_PREFS_PREF_MODEL_ASSOCIATOR_H_
 
 #include <map>
 #include <set>
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/threading/non_thread_safe.h"
 #include "sync/api/sync_data.h"
 #include "sync/api/syncable_service.h"
 
+class PrefRegistrySyncable;
 class PrefServiceSyncable;
 
 namespace sync_pb {
 class PreferenceSpecifics;
 }
 
 namespace base {
 class Value;
 }
 
@@ skipping 121 matching lines @@
   // Sync's syncer::SyncChange handler. We push all our changes through this.
   scoped_ptr<syncer::SyncChangeProcessor> sync_processor_;
 
   // Sync's error handler. We use this to create sync errors.
   scoped_ptr<syncer::SyncErrorFactory> sync_error_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(PrefModelAssociator);
 };
 
 #endif  // CHROME_BROWSER_PREFS_PREF_MODEL_ASSOCIATOR_H_