[ew] Move operation observers from QuotaUtil to FileSystemBackend.

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 350 matching lines @@
           context->default_file_task_runner(),
           url.path(),
           offset,
           storage::FileStreamWriter::OPEN_EXISTING_FILE));
 }
 
 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;
+}