[SyncFS] Remove using MessageLoop in worker thread

chrome/browser/sync_file_system/drive_backend/sync_engine_initializer_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/sync_engine_initializer.h"
 
 #include "base/bind.h"
 #include "base/files/scoped_temp_dir.h"
 #include "base/run_loop.h"
 #include "chrome/browser/drive/drive_api_util.h"
@@ skipping 59 matching lines @@
     sync_context_.reset();
     base::RunLoop().RunUntilIdle();
   }
 
   base::FilePath database_path() {
     return database_dir_.path();
   }
 
   SyncStatusCode RunInitializer() {
     SyncEngineInitializer* initializer =
-        new SyncEngineInitializer(
-            sync_context_.get(),
-            base::MessageLoopProxy::current(),
-            database_path(),
-            in_memory_env_.get());
+        new SyncEngineInitializer(sync_context_.get(),
+                                  database_path(),
+                                  in_memory_env_.get());
     SyncStatusCode status = SYNC_STATUS_UNKNOWN;
 
     sync_task_manager_->ScheduleSyncTask(
         FROM_HERE,
         scoped_ptr<SyncTask>(initializer),
         SyncTaskManager::PRIORITY_MED,
         base::Bind(&SyncEngineInitializerTest::DidRunInitializer,
                    base::Unretained(this), initializer, &status));
 
     base::RunLoop().RunUntilIdle();
@@ skipping 258 matching lines @@
 
   EXPECT_EQ(0u, CountTrackersForFile(sync_root->file_id()));
   EXPECT_FALSE(HasNoParent(sync_root->file_id()));
 
   EXPECT_EQ(1u, CountFileMetadata());
   EXPECT_EQ(1u, CountFileTracker());
 }
 
 }  // namespace drive_backend
 }  // namespace sync_file_system