Make MediaFileUtil run on thread pool.

webkit/fileapi/media/device_media_file_util.cc

 // Copyright (c) 2012 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 "webkit/fileapi/media/device_media_file_util.h"
 
 #include "base/file_util.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop_proxy.h"
 #include "webkit/blob/shareable_file_reference.h"
@@ skipping 176 matching lines @@
   bool file_created = file_util::CreateTemporaryFileInDir(
       isolated_media_file_system_dir_path, local_path);
   if (!file_created)
     return file_ref;
 
   *result = context->media_device()->CreateSnapshotFile(url.path(), *local_path,
                                                         file_info);
   if (*result == base::PLATFORM_FILE_OK) {
     file_ref = ShareableFileReference::GetOrCreate(
         *local_path, ShareableFileReference::DELETE_ON_FINAL_RELEASE,
-        context->file_task_runner());
+        context->task_runner());
   }
   return file_ref;
 }
 
 }  // namespace fileapi