[SyncFS] Run RemoteToLocalSyncer as a background task

chrome/browser/sync_file_system/drive_backend/remote_to_local_syncer.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_REMOTE_TO_LOCAL_SYNCER_H_
 #define CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_REMOTE_TO_LOCAL_SYNCER_H_
 
 #include <string>
 #include <vector>
 
 #include "base/memory/scoped_vector.h"
 #include "base/memory/weak_ptr.h"
 #include "chrome/browser/sync_file_system/drive_backend/metadata_database.pb.h"
 #include "chrome/browser/sync_file_system/drive_backend/sync_task.h"
+#include "chrome/browser/sync_file_system/drive_backend/sync_task_manager.h"
 #include "chrome/browser/sync_file_system/remote_change_processor.h"
 #include "chrome/browser/sync_file_system/sync_action.h"
 #include "chrome/browser/sync_file_system/sync_callbacks.h"
 #include "chrome/browser/sync_file_system/sync_file_metadata.h"
 #include "google_apis/drive/gdata_errorcode.h"
 #include "storage/browser/fileapi/file_system_url.h"
 
 namespace drive {
 class DriveServiceInterface;
 }
 
 namespace google_apis {
 class FileList;
 class FileResource;
 class ResourceEntry;
 }
 
 namespace storage {
 class ScopedFile;
 }
 
 namespace sync_file_system {
 namespace drive_backend {
 
 class MetadataDatabase;
 class SyncEngineContext;
 
 class RemoteToLocalSyncer : public SyncTask {
  public:
+  typedef SyncTaskManager::Continuation Continuation;
+
   // Conflicting trackers will have low priority for RemoteToLocalSyncer so that
   // it should be resolved by LocatToRemoteSyncer.
   explicit RemoteToLocalSyncer(SyncEngineContext* sync_context);
   virtual ~RemoteToLocalSyncer();
 
   virtual void RunPreflight(scoped_ptr<SyncTaskToken> token) OVERRIDE;
   void RunExclusive(scoped_ptr<SyncTaskToken> token);
 
   const storage::FileSystemURL& url() const { return url_; }
   SyncAction sync_action() const { return sync_action_; }
@@ skipping 41 matching lines @@
   // Else, if the folder is a regular file and the md5 in remote metadata does
   // not match the md5 in synced metadata:
   //   # The file is modified remotely.
   //   - Dispatch to HandleContentUpdate().
   // Else, if the tracker is a folder and it has needs_folder_listing flag:
   //   - Dispatch to HandleFolderContentListing()
   // Else, there should be no change to sync.
   //   - Dispatch to HandleOfflineSolvable()
   void ResolveRemoteChange(scoped_ptr<SyncTaskToken> token);
 
+  void MoveToBackground(scoped_ptr<SyncTaskToken> token,
+                        const Continuation& continuation);
+  void ContinueAsBackgroundTask(const Continuation& continuation,
+                                scoped_ptr<SyncTaskToken> token);
+
   // Handles missing remote metadata case.
   // Fetches remote metadata and updates MetadataDatabase by that.  The sync
   // operation itself will be deferred to the next sync round.
   // Note: if the file is not found, it should be handled as if deleted.
   void HandleMissingRemoteMetadata(scoped_ptr<SyncTaskToken> token);
   void DidGetRemoteMetadata(scoped_ptr<SyncTaskToken> token,
                             google_apis::GDataErrorCode error,
                             scoped_ptr<google_apis::FileResource> entry);
 
   // This implements the body of the HandleNewFile and HandleContentUpdate.
@@ skipping 10 matching lines @@
   //    defer further handling to local-to-remote change.
   void DidPrepareForAddOrUpdateFile(scoped_ptr<SyncTaskToken> token,
                                     SyncStatusCode status);
 
   // Handles remotely added folder.  Needs Prepare() call.
   // TODO(tzik): Write details and implement this.
   void HandleFolderUpdate(scoped_ptr<SyncTaskToken> token);
   void DidPrepareForFolderUpdate(scoped_ptr<SyncTaskToken> token,
                                  SyncStatusCode status);
 
-  void HandleSyncRootDeletion(scoped_ptr<SyncTaskToken> token);
-
   // Handles deleted remote file.  Needs Prepare() call.
   // If the deleted tracker is the sync-root:
   //  - TODO(tzik): Needs special handling.
   // Else, if the deleted tracker is a app-root:
   //  - TODO(tzik): Needs special handling.
   // Else, if the local file is already deleted:
   //  - Do nothing anymore to the local, call SyncCompleted().
   // Else, if the local file is modified:
   //  - Do nothing to the local file, call SyncCompleted().
   // Else, if the local file is not modified:
   //  - Delete local file.
   //  # Note: if the local file is a folder, delete recursively.
   void HandleDeletion(scoped_ptr<SyncTaskToken> token);
   void DidPrepareForDeletion(scoped_ptr<SyncTaskToken> token,
                              SyncStatusCode status);
 
+  void HandleFileMove(scoped_ptr<SyncTaskToken> token);
+
   // Handles new file.  Needs Prepare() call.
   void HandleContentUpdate(scoped_ptr<SyncTaskToken> token);
 
   void ListFolderContent(scoped_ptr<SyncTaskToken> token);
   void DidListFolderContent(
       scoped_ptr<SyncTaskToken> token,
       scoped_ptr<FileIDList> children,
       google_apis::GDataErrorCode error,
       scoped_ptr<google_apis::FileList> file_list);
 
@@ skipping 42 matching lines @@
 
   base::WeakPtrFactory<RemoteToLocalSyncer> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(RemoteToLocalSyncer);
 };
 
 }  // namespace drive_backend
 }  // namespace sync_file_system
 
 #endif  // CHROME_BROWSER_SYNC_FILE_SYSTEM_DRIVE_BACKEND_REMOTE_TO_LOCAL_SYNCER_H_