[SyncFS] Remove using MessageLoop in worker thread

chrome/browser/sync_file_system/drive_backend/sync_worker.cc

 // Copyright 2014 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_worker.h"
 
 #include <vector>
 
 #include "base/bind.h"
 #include "base/memory/weak_ptr.h"
@@ skipping 409 matching lines @@
   }
 }
 
 void SyncWorker::PostInitializeTask() {
   DCHECK(!GetMetadataDatabase());
 
   // This initializer task may not run if MetadataDatabase in context_ is
   // already initialized when it runs.
   SyncEngineInitializer* initializer =
       new SyncEngineInitializer(context_.get(),
-                                context_->GetFileTaskRunner(),
                                 base_dir_.Append(kDatabaseName),
                                 env_override_);
   task_manager_->ScheduleSyncTask(
       FROM_HERE,
       scoped_ptr<SyncTask>(initializer),
       SyncTaskManager::PRIORITY_HIGH,
       base::Bind(&SyncWorker::DidInitialize,
                  weak_ptr_factory_.GetWeakPtr(),
                  initializer));
 }
@@ skipping 265 matching lines @@
             "Service state changed: %d->%d: %s",
             old_state, GetCurrentState(), description.c_str());
 
   FOR_EACH_OBSERVER(
       Observer, observers_,
       UpdateServiceState(GetCurrentState(), description));
 }
 
 }  // namespace drive_backend
 }  // namespace sync_file_system