IndexedDB: Fixed support for empty blobs.

chrome/browser/media_galleries/fileapi/media_file_system_backend.cc

 // Copyright (c) 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/media_galleries/fileapi/media_file_system_backend.h"
 
 #include <string>
 #include <vector>
 
 #include "base/bind.h"
@@ skipping 341 matching lines @@
           expected_modification_time));
 }
 
 scoped_ptr<storage::FileStreamWriter>
 MediaFileSystemBackend::CreateFileStreamWriter(
     const FileSystemURL& url,
     int64 offset,
     FileSystemContext* context) const {
   return scoped_ptr<storage::FileStreamWriter>(
       storage::FileStreamWriter::CreateForLocalFile(
-          context->default_file_task_runner(),
-          url.path(),
-          offset,
-          storage::FileStreamWriter::OPEN_EXISTING_FILE));
+          context->default_file_task_runner(), url.path(), offset));
 }
 
 storage::FileSystemQuotaUtil* MediaFileSystemBackend::GetQuotaUtil() {
   // No quota support.
   return NULL;
 }
 
 const storage::UpdateObserverList* MediaFileSystemBackend::GetUpdateObservers(
     storage::FileSystemType type) const {
   return NULL;
 }
 
 const storage::ChangeObserverList* MediaFileSystemBackend::GetChangeObservers(
     storage::FileSystemType type) const {
   return NULL;
 }
 
 const storage::AccessObserverList* MediaFileSystemBackend::GetAccessObservers(
     storage::FileSystemType type) const {
   return NULL;
 }