[SyncFS] Add completion callback to PromoteDemotedChanges (1/3)

chrome/browser/sync_file_system/drive_backend/sync_engine.h

 // Copyright 2013 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_SYNC_FILE_SYSTEM_DRIVE_BACKEND_SYNC_ENGINE_H_
 #define CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_SYNC_ENGINE_H_
 
 #include <set>
 #include <string>
 
@@ skipping 94 matching lines @@
   virtual void ProcessRemoteChange(const SyncFileCallback& callback) OVERRIDE;
   virtual void SetRemoteChangeProcessor(
       RemoteChangeProcessor* processor) OVERRIDE;
   virtual LocalChangeProcessor* GetLocalChangeProcessor() OVERRIDE;
   virtual RemoteServiceState GetCurrentState() const OVERRIDE;
   virtual void GetOriginStatusMap(const StatusMapCallback& callback) OVERRIDE;
   virtual void DumpFiles(const GURL& origin,
                          const ListCallback& callback) OVERRIDE;
   virtual void DumpDatabase(const ListCallback& callback) OVERRIDE;
   virtual void SetSyncEnabled(bool enabled) OVERRIDE;
-  virtual void PromoteDemotedChanges() OVERRIDE;
+  virtual void PromoteDemotedChanges(const base::Closure& callback) OVERRIDE;
 
   // LocalChangeProcessor overrides.
   virtual void ApplyLocalChange(
       const FileChange& local_change,
       const base::FilePath& local_path,
       const SyncFileMetadata& local_metadata,
       const fileapi::FileSystemURL& url,
       const SyncStatusCallback& callback) OVERRIDE;
 
   // drive::DriveNotificationObserver overrides.
@@ skipping 87 matching lines @@
   CallbackTracker callback_tracker_;
 
   base::WeakPtrFactory<SyncEngine> weak_ptr_factory_;
   DISALLOW_COPY_AND_ASSIGN(SyncEngine);
 };
 
 }  // namespace drive_backend
 }  // namespace sync_file_system
 
 #endif  // CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_SYNC_ENGINE_H_