[SyncFS] Drop TaskRunner in MetadataDatabase

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 "base/thread_task_runner_handle.h"
@@ skipping 91 matching lines @@
     metadata_database_ = initializer->PassMetadataDatabase();
   }
 
   SyncStatusCode PopulateDatabase(
       const google_apis::FileResource& sync_root,
       const google_apis::FileResource** app_roots,
       size_t app_roots_count) {
     SyncStatusCode status = SYNC_STATUS_UNKNOWN;
     scoped_ptr<MetadataDatabase> database;
     MetadataDatabase::Create(
-        base::ThreadTaskRunnerHandle::Get(),
         database_path(),
         in_memory_env_.get(),
         CreateResultReceiver(&status, &database));
     base::RunLoop().RunUntilIdle();
     if (status != SYNC_STATUS_OK)
       return status;
 
     // |app_root_list| must not own the resources here. Be sure to call
     // weak_clear later.
     ScopedVector<google_apis::FileResource> app_root_list;
@@ skipping 227 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