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

chrome/browser/sync_file_system/drive_backend/sync_engine.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/sync_engine.h"
 
 #include <vector>
 
 #include "base/bind.h"
 #include "base/metrics/histogram.h"
@@ skipping 163 matching lines @@
     TaskLogger* task_logger) {
   scoped_refptr<base::SequencedWorkerPool> worker_pool =
       content::BrowserThread::GetBlockingPool();
 
   scoped_refptr<base::SingleThreadTaskRunner> ui_task_runner =
       base::ThreadTaskRunnerHandle::Get();
   scoped_refptr<base::SequencedTaskRunner> worker_task_runner =
       worker_pool->GetSequencedTaskRunnerWithShutdownBehavior(
           worker_pool->GetSequenceToken(),
           base::SequencedWorkerPool::SKIP_ON_SHUTDOWN);
-  scoped_refptr<base::SequencedTaskRunner> file_task_runner =
-      worker_pool->GetSequencedTaskRunnerWithShutdownBehavior(
-          worker_pool->GetSequenceToken(),
-          base::SequencedWorkerPool::SKIP_ON_SHUTDOWN);
   scoped_refptr<base::SequencedTaskRunner> drive_task_runner =
       worker_pool->GetSequencedTaskRunnerWithShutdownBehavior(
           worker_pool->GetSequenceToken(),
           base::SequencedWorkerPool::SKIP_ON_SHUTDOWN);
 
   Profile* profile = Profile::FromBrowserContext(context);
   drive::DriveNotificationManager* notification_manager =
       drive::DriveNotificationManagerFactory::GetForBrowserContext(context);
   ExtensionService* extension_service =
       extensions::ExtensionSystem::Get(context)->extension_service();
   SigninManagerBase* signin_manager =
       SigninManagerFactory::GetForProfile(profile);
   ProfileOAuth2TokenService* token_service =
       ProfileOAuth2TokenServiceFactory::GetForProfile(profile);
   scoped_refptr<net::URLRequestContextGetter> request_context =
       context->GetRequestContext();
 
   scoped_ptr<drive_backend::SyncEngine> sync_engine(
       new SyncEngine(ui_task_runner,
                      worker_task_runner,
-                     file_task_runner,
                      drive_task_runner,
                      GetSyncFileSystemDir(context->GetPath()),
                      task_logger,
                      notification_manager,
                      extension_service,
                      signin_manager,
                      token_service,
                      request_context,
                      NULL  /* env_override */));
 
@@ skipping 95 matching lines @@
                                worker_task_runner_));
   scoped_ptr<drive::DriveUploaderInterface> drive_uploader_on_worker(
       new DriveUploaderOnWorker(drive_uploader_wrapper_->AsWeakPtr(),
                                 ui_task_runner_,
                                 worker_task_runner_));
   scoped_ptr<SyncEngineContext> sync_engine_context(
       new SyncEngineContext(drive_service_on_worker.Pass(),
                             drive_uploader_on_worker.Pass(),
                             task_logger_,
                             ui_task_runner_,
-                            worker_task_runner_,
-                            file_task_runner_));
+                            worker_task_runner_));
 
   worker_observer_.reset(
       new WorkerObserver(ui_task_runner_, weak_ptr_factory_.GetWeakPtr()));
 
   base::WeakPtr<ExtensionServiceInterface> extension_service_weak_ptr;
   if (extension_service_)
     extension_service_weak_ptr = extension_service_->AsWeakPtr();
 
   if (!sync_worker) {
     sync_worker.reset(new SyncWorker(
@@ skipping 370 matching lines @@
 
 void SyncEngine::GoogleSignedOut(const std::string& username) {
   Reset();
   UpdateServiceState(REMOTE_SERVICE_AUTHENTICATION_REQUIRED,
                      "User signed out.");
 }
 
 SyncEngine::SyncEngine(
     base::SingleThreadTaskRunner* ui_task_runner,
     base::SequencedTaskRunner* worker_task_runner,
-    base::SequencedTaskRunner* file_task_runner,
     base::SequencedTaskRunner* drive_task_runner,
     const base::FilePath& sync_file_system_dir,
     TaskLogger* task_logger,
     drive::DriveNotificationManager* notification_manager,
     ExtensionServiceInterface* extension_service,
     SigninManagerBase* signin_manager,
     ProfileOAuth2TokenService* token_service,
     net::URLRequestContextGetter* request_context,
     leveldb::Env* env_override)
     : ui_task_runner_(ui_task_runner),
       worker_task_runner_(worker_task_runner),
-      file_task_runner_(file_task_runner),
       drive_task_runner_(drive_task_runner),
       sync_file_system_dir_(sync_file_system_dir),
       task_logger_(task_logger),
       notification_manager_(notification_manager),
       extension_service_(extension_service),
       signin_manager_(signin_manager),
       token_service_(token_service),
       request_context_(request_context),
       remote_change_processor_(NULL),
       service_state_(REMOTE_SERVICE_TEMPORARY_UNAVAILABLE),
@@ skipping 38 matching lines @@
 
 SyncStatusCallback SyncEngine::TrackCallback(
     const SyncStatusCallback& callback) {
   return callback_tracker_.Register(
       base::Bind(callback, SYNC_STATUS_ABORT),
       callback);
 }
 
 }  // namespace drive_backend
 }  // namespace sync_file_system