Use PageManager in About page

chrome/browser/resources/options/options_page.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() {
   /** @const */ var FocusOutlineManager = cr.ui.FocusOutlineManager;
   /** @const */ var PageManager = cr.ui.pageManager.PageManager;
 
   var OptionsPage = {
     /**
      * This is the absolute difference maintained between standard and
      * fixed-width font sizes. Refer http://crbug.com/91922.
      * @const
      */
     SIZE_DIFFERENCE_FIXED_STANDARD: 3,
 
     /**
      * Initializes the complete options page. This will cause all C++ handlers
      * to be invoked to do final setup.
      */
     initialize: function() {
       chrome.send('coreOptionsInitialize');
-      uber.onContentFrameLoaded();
       PageManager.initialize(BrowserOptions.getInstance());
     },
 
     /**
      * Shows the tab contents for the given navigation tab.
      * @param {!Element} tab The tab that the user clicked.
      */
     showTab: function(tab) {
       // Search parents until we find a tab, or the nav bar itself. This allows
       // tabs to have child nodes, e.g. labels in separately-styled spans.
@@ skipping 70 matching lines @@
     isSettingsApp: function() {
       return document.documentElement.classList.contains('settings-app');
     },
   };
 
   // Export
   return {
     OptionsPage: OptionsPage
   };
 });