[SyncFS] Make MetadataDatabase operations synchronous

chrome/browser/sync_file_system/drive_backend/folder_creator.cc

 // 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.
 
 #include "chrome/browser/sync_file_system/drive_backend/folder_creator.h"
 
 #include "chrome/browser/drive/drive_api_util.h"
 #include "chrome/browser/drive/drive_service_interface.h"
 #include "chrome/browser/sync_file_system/drive_backend/drive_backend_util.h"
 #include "chrome/browser/sync_file_system/drive_backend/metadata_database.h"
@@ skipping 95 matching lines @@
       oldest = &entry;
   }
 
   if (!oldest) {
     callback.Run(std::string(), SYNC_FILE_ERROR_NOT_FOUND);
     return;
   }
 
   std::string file_id = oldest->file_id();
 
-  metadata_database_->UpdateByFileResourceList(
-      candidates.Pass(), base::Bind(&FolderCreator::DidUpdateDatabase,
-                                    weak_ptr_factory_.GetWeakPtr(),
-                                    file_id, callback));
+  status = metadata_database_->UpdateByFileResourceList(candidates.Pass());
+
+  // TODO(tzik): Expand this function.
+  DidUpdateDatabase(file_id, callback, status);
 }
 
 void FolderCreator::DidUpdateDatabase(const std::string& file_id,
                                       const FileIDCallback& callback,
                                       SyncStatusCode status) {
   if (status != SYNC_STATUS_OK) {
     callback.Run(std::string(), status);
     return;
   }
 
   DCHECK(!file_id.empty());
   if (!metadata_database_->FindFileByFileID(file_id, NULL)) {
     callback.Run(std::string(), SYNC_FILE_ERROR_NOT_FOUND);
     return;
   }
 
   callback.Run(file_id, status);
 }
 
 }  // namespace drive_backend
 }  // namespace sync_file_system