[SyncFS] Remove usage of file task runner under drive_backend/

chrome/browser/sync_file_system/drive_backend/register_app_task_unittest.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/register_app_task.h"
 
 #include <vector>
 
 #include "base/files/scoped_temp_dir.h"
 #include "base/format_macros.h"
@@ skipping 46 matching lines @@
     fake_drive_service_helper_.reset(new FakeDriveServiceHelper(
         fake_drive_service.get(), drive_uploader.get(),
         kSyncRootFolderTitle));
 
     context_.reset(
         new SyncEngineContext(
             fake_drive_service.PassAs<drive::DriveServiceInterface>(),
             drive_uploader.Pass(),
             NULL,
             base::ThreadTaskRunnerHandle::Get(),
-            base::ThreadTaskRunnerHandle::Get(),
             base::ThreadTaskRunnerHandle::Get()));
 
     ASSERT_EQ(google_apis::HTTP_CREATED,
               fake_drive_service_helper_->AddOrphanedFolder(
                   kSyncRootFolderTitle, &sync_root_folder_id_));
   }
 
   virtual void TearDown() OVERRIDE {
     context_.reset();
     base::RunLoop().RunUntilIdle();
@@ skipping 232 matching lines @@
 
   CreateMetadataDatabase(db.Pass());
   RunRegisterAppTask(kAppID);
 
   EXPECT_EQ(1u, CountRegisteredAppRoot());
   EXPECT_TRUE(IsAppRegistered(kAppID));
 }
 
 }  // namespace drive_backend
 }  // namespace sync_file_system