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

chrome/browser/resources/options2/browser_options.js

 // 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.
 
 cr.define('options', function() {
   var OptionsPage = options.OptionsPage;
   var ArrayDataModel = cr.ui.ArrayDataModel;
   var RepeatingButton = cr.ui.RepeatingButton;
 
   //
@@ skipping 83 matching lines @@
           'change', this.onHomePageSelectChange_.bind(this));
 
       ['browser.show_home_button',
           'homepage',
           'homepage_is_newtabpage'].forEach(function(pref) {
         Preferences.getInstance().addEventListener(
             pref,
             self.onHomePagePrefChanged_.bind(self));
       });
 
+      if ($('set-wallpaper')) {
+        $('set-wallpaper').onclick = function(event) {
+          OptionsPage.navigateToPage('setWallpaper');
+        };
+      }
+
       $('themes-gallery').onclick = function(event) {
         window.open(localStrings.getString('themesGalleryURL'));
       };
       $('themes-reset').onclick = function(event) {
         chrome.send('themesReset');
       };
 
       // Device section (ChromeOS only).
       if (cr.isChromeOS) {
         $('keyboard-settings-button').onclick = function(evt) {
@@ skipping 1101 matching lines @@
     BrowserOptions.getLoggedInUsername = function() {
       return BrowserOptions.getInstance().username_;
     };
   }
 
   // Export
   return {
     BrowserOptions: BrowserOptions
   };
 });