Ensure WebView notifies desktop automation on creation, destruction, and change

chrome/browser/resources/chromeos/chromevox/testing/chromevox_next_e2e_test_base.js

 // Copyright 2014 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.
 
 // Include test fixture.
 GEN_INCLUDE(['chrome/browser/resources/chromeos/chromevox/testing/' +
     'chromevox_e2e_test_base.js']);
 
 /**
  * Base test fixture for ChromeVox Next end to end tests.
@@ skipping 14 matching lines @@
    * @override
    */
   testGenCppIncludes: function() {
     ChromeVoxE2ETest.prototype.testGenCppIncludes.call(this);
     GEN('#include "base/command_line.h"');
   },
 
   runWithAutomation: function(doc, callback) {
     this.runWithDocument(doc, function() {
       chrome.automation.getTree(function(root) {
-        callback(root);
+        if (root.children.length == 0) {
+          root.addEventListener('loadComplete',
+                                function() {
+                                  callback(root);
+                                }.bind(this), true);
+        } else {
+          callback(root);
+        }
       }.bind(this));
     }.bind(this));
   }
 };