[SyncFS] Fix unexpected delay on running sync task

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 340 matching lines @@
       FROM_HERE,
       base::Bind(&SyncWorkerInterface::Initialize,
                  base::Unretained(sync_worker_.get()),
                  base::Passed(&sync_engine_context)));
   if (remote_change_processor_)
     SetRemoteChangeProcessor(remote_change_processor_);
 
   drive_service_->AddObserver(this);
 
   service_state_ = REMOTE_SERVICE_TEMPORARY_UNAVAILABLE;
-  SetSyncEnabled(sync_enabled_);
   OnNetworkChanged(net::NetworkChangeNotifier::GetConnectionType());
   if (drive_service_->HasRefreshToken())
     OnReadyToSendRequests();
   else
     OnRefreshTokenInvalid();
 }
 
 void SyncEngine::AddServiceObserver(SyncServiceObserver* observer) {
   service_observers_.AddObserver(observer);
 }
@@ skipping 286 matching lines @@
     return;
 
   worker_task_runner_->PostTask(
       FROM_HERE,
       base::Bind(&SyncWorkerInterface::ActivateService,
                  base::Unretained(sync_worker_.get()),
                  REMOTE_SERVICE_OK,
                  "Got push notification for Drive"));
 }
 
-void SyncEngine::OnPushNotificationEnabled(bool) {}
+void SyncEngine::OnPushNotificationEnabled(bool /* enabled */) {}
 
 void SyncEngine::OnReadyToSendRequests() {
   has_refresh_token_ = true;
   if (!sync_worker_)
     return;
 
   worker_task_runner_->PostTask(
       FROM_HERE,
       base::Bind(&SyncWorkerInterface::ActivateService,
                  base::Unretained(sync_worker_.get()),
@@ skipping 124 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