[uber page] Split up initialization of handlers from initialization of webui pages

chrome/browser/resources/uber/uber_frame.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.
 
 // This file contains the navigation controls that are visible on the left side
 // of the uber page. It exists separately from uber.js so that it may be loaded
 // in an iframe. Iframes can be layered on top of each other, but not mixed in
 // with page content, so all overlapping content on uber must be framed.
 
 <include src="../shared/js/util.js"></include>
@@ skipping 16 matching lines @@
 
     document.documentElement.addEventListener('mousewheel', onMouseWheel);
   }
 
   /**
    * Handles clicks on the navigation controls (switches the page and updates
    * the URL).
    * @param {Event} e The click event.
    */
   function onNavItemClicked(e) {
+    assert(!e.target.classList.contains('selected'));
+
     uber.invokeMethodOnParent('showPage',
        {pageId: e.currentTarget.getAttribute('controls')});
 
     setSelection(e.currentTarget);
   }
 
   /**
    * Handles postMessage from chrome://chrome.
    * @param {Event} e The post data.
    */
@@ skipping 70 matching lines @@
     return document.querySelector('.iframe-container.selected');
   }
 
   return {
     onLoad: onLoad,
   };
 
 });
 
 document.addEventListener('DOMContentLoaded', uber_frame.onLoad);