Remeber active tab in tab bar instead of 'this'.

chrome/browser/resources/options/options_page.js

 // Copyright (c) 2011 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() {
   /////////////////////////////////////////////////////////////////////////////
   // OptionsPage class:
 
   /**
    * Base class for options page.
@@ skipping 320 matching lines @@
   OptionsPage.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.
     while (tab && !tab.classList.contains('subpages-nav-tabs') &&
            !tab.classList.contains('tab')) {
       tab = tab.parentNode;
     }
     if (!tab || !tab.classList.contains('tab'))
       return;
 
-    if (this.activeNavTab != null) {
-      this.activeNavTab.classList.remove('active-tab');
-      $(this.activeNavTab.getAttribute('tab-contents')).classList.
+    // Find tab bar of the tab.
+    var tabBar = tab;
+    while (tabBar && !tabBar.classList.contains('subpages-nav-tabs')) {
+      tabBar = tabBar.parentNode;
+    }
+    if (!tabBar)
+      return;
+
+    if (tabBar.activeNavTab != null) {
+      tabBar.activeNavTab.classList.remove('active-tab');
+      $(tabBar.activeNavTab.getAttribute('tab-contents')).classList.
           remove('active-tab-contents');
     }
 
     tab.classList.add('active-tab');
     $(tab.getAttribute('tab-contents')).classList.add('active-tab-contents');
-    this.activeNavTab = tab;
+    tabBar.activeNavTab = tab;
   };
 
   /**
    * Registers new options page.
    * @param {OptionsPage} page Page to register.
    */
   OptionsPage.register = function(page) {
     this.registeredPages[page.name.toLowerCase()] = page;
     // Create and add new page <li> element to navbar.
     var pageNav = document.createElement('li');
@@ skipping 658 matching lines @@
     canShowPage: function() {
       return true;
     },
   };
 
   // Export
   return {
     OptionsPage: OptionsPage
   };
 });