[SyncFS] Remove using MessageLoop in worker thread

chrome/browser/sync_file_system/drive_backend/sync_engine_initializer.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_initializer.h"
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/logging.h"
 #include "base/message_loop/message_loop_proxy.h"
@@ skipping 59 matching lines @@
   return resources.Pass();
 }
 
 // Functions above are for wrapping the access to legacy GData WAPI classes.
 ////////////////////////////////////////////////////////////////////////////////
 
 }  // namespace
 
 SyncEngineInitializer::SyncEngineInitializer(
     SyncEngineContext* sync_context,
-    base::SequencedTaskRunner* task_runner,
     const base::FilePath& database_path,
     leveldb::Env* env_override)
     : sync_context_(sync_context),
       env_override_(env_override),
-      task_runner_(task_runner),
       database_path_(database_path),
       find_sync_root_retry_count_(0),
       largest_change_id_(0),
       weak_ptr_factory_(this) {
   DCHECK(sync_context);
-  DCHECK(task_runner);
 }
 
 SyncEngineInitializer::~SyncEngineInitializer() {
   if (!cancel_callback_.is_null())
     cancel_callback_.Run();
 }
 
 void SyncEngineInitializer::RunPreflight(scoped_ptr<SyncTaskToken> token) {
   util::Log(logging::LOG_VERBOSE, FROM_HERE, "[Initialize] Start.");
   DCHECK(sync_context_);
   DCHECK(sync_context_->GetDriveService());
 
   // The metadata seems to have been already initialized. Just return with OK.
   if (sync_context_->GetMetadataDatabase()) {
     util::Log(logging::LOG_VERBOSE, FROM_HERE,
               "[Initialize] Already initialized.");
     SyncTaskManager::NotifyTaskDone(token.Pass(), SYNC_STATUS_OK);
     return;
   }
 
-  // TODO(tzik): Stop using MessageLoopProxy before moving out from UI thread.
-  scoped_refptr<base::SequencedTaskRunner> worker_task_runner(
-      base::MessageLoopProxy::current());
-
   MetadataDatabase::Create(
-      worker_task_runner.get(),
-      task_runner_.get(), database_path_, env_override_,
+      sync_context_->GetWorkerTaskRunner(),
+      sync_context_->GetFileTaskRunner(),
+      database_path_,
+      env_override_,
       base::Bind(&SyncEngineInitializer::DidCreateMetadataDatabase,
                  weak_ptr_factory_.GetWeakPtr(), base::Passed(&token)));
 }
 
 scoped_ptr<MetadataDatabase> SyncEngineInitializer::PassMetadataDatabase() {
   return metadata_database_.Pass();
 }
 
 void SyncEngineInitializer::DidCreateMetadataDatabase(
     scoped_ptr<SyncTaskToken> token,
@@ skipping 269 matching lines @@
     return;
   }
 
   util::Log(logging::LOG_VERBOSE, FROM_HERE,
             "[Initialize] Completed successfully.");
   SyncTaskManager::NotifyTaskDone(token.Pass(), SYNC_STATUS_OK);
 }
 
 }  // namespace drive_backend
 }  // namespace sync_file_system