Properly launch the connectivity diagnostics app from the offline page

chrome/browser/resources/chromeos/neterror.js

 // Copyright 2013 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.
 
 function toggleHelpBox() {
   var helpBoxOuter = $('help-box-outer');
   helpBoxOuter.classList.toggle('hidden');
   var moreLessButton = $('more-less-button');
   if (helpBoxOuter.classList.contains('hidden')) {
     moreLessButton.innerText = moreLessButton.moreText;
   } else {
     moreLessButton.innerText = moreLessButton.lessText;
   }
 }
 
 function diagnoseErrors() {
-  var extensionId = 'idddmepepmjcgiedknnmlbadcokidhoa';
-  var diagnoseFrame = $('diagnose-frame');
-  diagnoseFrame.innerHTML =
-      '<iframe src="chrome-extension://' + extensionId +
-      '/index.html"></iframe>';
+  window.domAutomationController.setAutomationId(1);
+  window.domAutomationController.send('open_connectivity_diagnostics');
 }
 
 // Subframes use a different layout but the same html file.  This is to make it
 // easier to support platforms that load the error page via different
 // mechanisms (Currently just iOS).
 if (window.top.location != window.location)
   document.documentElement.setAttribute('subframe', '');
 
 // Re-renders the error page using |strings| as the dictionary of values.
 // Used by NetErrorTabHelper to update DNS error pages with probe results.
@@ skipping 13 matching lines @@
     if (oldClass == newClass)
       return;
   }
 
   classList.add(newClass);
   if (oldClass !== undefined)
     classList.remove(oldClass);
 
   classList['last_icon_class'] = newClass;
 }