Disables the ability to tab to navigation items when an overlay is displayed.

chrome/browser/resources/uber/uber.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('uber', function() {
   var localStrings = new LocalStrings();
 
   /**
    * Options for how web history should be handled.
    */
@@ skipping 133 matching lines @@
       forwardMouseWheel(e.data.params);
     else
       console.error('Received unexpected message', e.data);
   }
 
   /**
    * Sends the navigation iframe to the background.
    */
   function backgroundNavigation() {
     navFrame.classList.add('background');
+    setNavigationItemTabbing(false);
   }
 
   /**
    * Retrieves the navigation iframe from the background.
    */
   function foregroundNavigation() {
     navFrame.classList.remove('background');
+    setNavigationItemTabbing(true);
   }
 
   /**
    * Enables or disables animated transitions when changing content while
    * horizontally scrolled.
    * @param {boolean} enabled True if enabled, else false to disable.
    */
   function setContentChanging(enabled) {
     navFrame.classList[enabled ? 'add' : 'remove']('changing-content');
 
@@ skipping 152 matching lines @@
 
   /**
    * Forward scroll wheel events to subpages.
    * @param {Object} params Relevant parameters of wheel event.
    */
   function forwardMouseWheel(params) {
     var iframe = getSelectedIframe().querySelector('iframe');
     uber.invokeMethodOnWindow(iframe.contentWindow, 'mouseWheel', params);
   }
 
+  /**
+   * Enables or disables the ability to tab to the navigation items.
+   * @param {boolean} enabled If true, enables tabbing; if false, disables it.
+   */
+  function setNavigationItemTabbing(enabled) {

[Evan Stade, 2012/05/08 23:51:31]

I don't think this function is necessary. Just split the relevant parts into
background/foregroundNavigation

[Kyle Horimoto, 2012/05/09 00:02:19]

Done.

+    navFrame.firstChild.tabIndex = enabled ? 0 : -1;
+    if (enabled)
+      navFrame.firstChild.removeAttribute('aria-hidden');
+    else
+      navFrame.firstChild.setAttribute('aria-hidden', true);
+  }
+
   return {
     onLoad: onLoad,
     onPopHistoryState: onPopHistoryState
   };
 });
 
 window.addEventListener('popstate', uber.onPopHistoryState);
 document.addEventListener('DOMContentLoaded', uber.onLoad);