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

chrome/renderer/resources/extensions/automation/automation_node.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.
 
 var AutomationEvent = require('automationEvent').AutomationEvent;
 var automationInternal =
     require('binding').Binding.create('automationInternal').generate();
 var IsInteractPermitted =
     requireNative('automationInternal').IsInteractPermitted;
 
@@ skipping 710 matching lines @@
     }
 
     return success;
   },
 
   setData_: function(node, nodeData) {
     var nodeImpl = privates(node).impl;
 
     // TODO(dtseng): Make into set listing all hosting node roles.
     if (nodeData.role == schema.RoleType.webView) {
-      if (nodeImpl.pendingChildFrame === undefined)
+      if (nodeImpl.childTreeID !== nodeData.intAttributes.childTreeId)
         nodeImpl.pendingChildFrame = true;
 
       if (nodeImpl.pendingChildFrame) {
         nodeImpl.childTreeID = nodeData.intAttributes.childTreeId;
         automationInternal.enableFrame(nodeImpl.childTreeID);
         automationUtil.storeTreeCallback(nodeImpl.childTreeID, function(root) {
           nodeImpl.pendingChildFrame = false;
           nodeImpl.childTree = root;
           privates(root).impl.hostTree = node;
           nodeImpl.dispatchEvent(schema.EventType.childrenChanged);
@@ skipping 241 matching lines @@
                                                'attributes',
                                                'indexInParent',
                                                'root'] });
 
 var AutomationRootNode = utils.expose('AutomationRootNode',
                                       AutomationRootNodeImpl,
                                       { superclass: AutomationNode });
 
 exports.AutomationNode = AutomationNode;
 exports.AutomationRootNode = AutomationRootNode;