Enable user change background image in settings page in Aura build.

chrome/common/chrome_notification_types.h

 // 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.
 
 #ifndef CHROME_COMMON_CHROME_NOTIFICATION_TYPES_H_
 #define CHROME_COMMON_CHROME_NOTIFICATION_TYPES_H_
 #pragma once
 
 #include "content/public/browser/notification_types.h"
 
@@ skipping 809 matching lines @@
   // Sent when a panel state changed.
   NOTIFICATION_PANEL_STATE_CHANGED,
 
   // Sent when the window manager's layout mode has changed.
   NOTIFICATION_LAYOUT_MODE_CHANGED,
 
   // Sent when the wizard's content view is destroyed. The source and details
   // are not used.
   NOTIFICATION_WIZARD_CONTENT_VIEW_DESTROYED,
 
+  // Sent when the user want to change desktop background.
+  NOTIFICATION_DESKTOP_BACKGROUND_CHANGED,
+
   // Sent when the screen lock state has changed. The source is
   // ScreenLocker and the details is a bool specifing that the
   // screen is locked. When details is a false, the source object
   // is being deleted, so the receiver shouldn't use the screen locker
   // object.
   NOTIFICATION_SCREEN_LOCK_STATE_CHANGED,
 
   // Sent when an attempt to acquire the public key of the owner of a chromium
   // os device has succeeded.
   NOTIFICATION_OWNER_KEY_FETCH_ATTEMPT_SUCCEEDED,
@@ skipping 187 matching lines @@
   // Currently only Content and Chrome define and use notifications.
   // Custom notifications not belonging to Content and Chrome should start
   // from here.
   NOTIFICATION_CHROME_END,
 };
 
 }  // namespace chrome
 
 
 #endif  // CHROME_COMMON_CHROME_NOTIFICATION_TYPES_H_