FileAPI: Factor out getting root URI and FS name parts into each FS backend

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 "base/bind.h"
 #include "base/files/file_path.h"
@@ skipping 93 matching lines @@
 }
 
 void MediaFileSystemBackend::OpenFileSystem(
     const GURL& origin_url,
     fileapi::FileSystemType type,
     fileapi::OpenFileSystemMode mode,
     const OpenFileSystemCallback& callback) {
   // We never allow opening a new isolated FileSystem via usual OpenFileSystem.
   base::MessageLoopProxy::current()->PostTask(
       FROM_HERE,
-      base::Bind(callback, base::PLATFORM_FILE_ERROR_SECURITY));
+      base::Bind(callback,
+                 GetFileSystemRootURI(origin_url, type),
+                 GetFileSystemName(origin_url, type),
+                 base::PLATFORM_FILE_ERROR_SECURITY));
 }
 
 fileapi::FileSystemFileUtil* MediaFileSystemBackend::GetFileUtil(
     fileapi::FileSystemType type) {
   NOTREACHED();
   return NULL;
 }
 
 fileapi::AsyncFileUtil* MediaFileSystemBackend::GetAsyncFileUtil(
     fileapi::FileSystemType type) {
@@ skipping 77 matching lines @@
           url.path(), offset));
 }
 
 fileapi::FileSystemQuotaUtil*
 MediaFileSystemBackend::GetQuotaUtil() {
   // No quota support.
   return NULL;
 }
 
 }  // namespace chrome