Add GetURLForBrowserTab method to the external file system backend.

chrome/browser/chromeos/fileapi/mtp_file_system_backend_delegate.cc

 // Copyright 2014 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/chromeos/fileapi/mtp_file_system_backend_delegate.h"
 #include "chrome/browser/media_galleries/fileapi/device_media_async_file_util.h"
 #include "webkit/browser/blob/file_stream_reader.h"
 #include "webkit/browser/fileapi/file_stream_writer.h"
 #include "webkit/browser/fileapi/file_system_url.h"
 
@@ skipping 38 matching lines @@
   // TODO(kinaba): support writing.
   return scoped_ptr<storage::FileStreamWriter>();
 }
 
 storage::WatcherManager* MTPFileSystemBackendDelegate::GetWatcherManager(
     const storage::FileSystemURL& url) {
   NOTIMPLEMENTED();
   return NULL;
 }
 
+void MTPFileSystemBackendDelegate::GetRedirectURLForContents(
+    const storage::FileSystemURL& url,
+    const storage::URLCallback& callback) {
+  DCHECK_EQ(storage::kFileSystemTypeDeviceMediaAsFileStorage, url.type());
+
+  callback.Run(GURL());
+}
+
 }  // namespace chromeos