[SyncFS] Implement Database initialization part of SyncEngineInitializer

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 "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
 #include "chrome/browser/drive/drive_notification_observer.h"
 #include "chrome/browser/sync_file_system/local_change_processor.h"
 #include "chrome/browser/sync_file_system/remote_file_sync_service.h"
 #include "chrome/browser/sync_file_system/sync_task_manager.h"
 
 class ExtensionService;
 
+namespace base {
+class SequencedTaskRunner;
+}
+
 namespace drive {
 class DriveAPIService;
 class DriveNotificationManager;
 }
 
 namespace sync_file_system {
 namespace drive_backend {
 
 class LocalToRemoteSyncer;
 class MetadataDatabase;
 class RemoteToLocalSyncer;
 class SyncEngineInitializer;
 
 class SyncEngine : public RemoteFileSyncService,
                    public LocalChangeProcessor,
                    public SyncTaskManager::Client,
                    public drive::DriveNotificationObserver {
  public:
   typedef Observer SyncServiceObserver;
 
   SyncEngine(const base::FilePath& base_dir,
+             base::SequencedTaskRunner* task_runner,
              scoped_ptr<drive::DriveAPIService> drive_api,
              drive::DriveNotificationManager* notification_manager,
              ExtensionService* extension_service);
   virtual ~SyncEngine();
 
   void Initialize();
 
   // RemoteFileSyncService overrides.
   virtual void AddServiceObserver(SyncServiceObserver* observer) OVERRIDE;
   virtual void AddFileStatusObserver(FileStatusObserver* observer) OVERRIDE;
@@ skipping 65 matching lines @@
   void DidProcessRemoteChange(RemoteToLocalSyncer* syncer,
                               const SyncFileCallback& callback,
                               SyncStatusCode status);
   void DidApplyLocalChange(LocalToRemoteSyncer* syncer,
                            const SyncStatusCallback& callback,
                            SyncStatusCode status);
 
   base::FilePath base_dir_;
   base::FilePath temporary_file_dir_;
 
+  scoped_refptr<base::SequencedTaskRunner> task_runner_;
+
   scoped_ptr<drive::DriveAPIService> drive_api_;
   scoped_ptr<MetadataDatabase> metadata_database_;
 
   // These external services are not owned by SyncEngine.
   // The owner of the SyncEngine is responsible for their lifetime.
   // I.e. the owner should declare the dependency explicitly by calling
   // BrowserContextKeyedService::DependsOn().
   drive::DriveNotificationManager* notification_manager_;
   ExtensionService* extension_service_;
 
   ObserverList<SyncServiceObserver> service_observers_;
   ObserverList<FileStatusObserver> file_status_observers_;
   RemoteChangeProcessor* remote_change_processor_;
 
   base::WeakPtrFactory<SyncEngine> weak_ptr_factory_;
   SyncTaskManager task_manager_;
 
   DISALLOW_COPY_AND_ASSIGN(SyncEngine);
 };
 
 }  // namespace drive_backend
 }  // namespace sync_file_system
 
 #endif  // CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_SYNC_ENGINE_H_