Add new version of enrollment screen supporting OAuth.

chrome/browser/resources/chromeos/login/screen_gaia_signin.js

 // Copyright (c) 2011 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.
 
 /**
  * @fileoverview Oobe signin screen implementation.
  */
 
 cr.define('login', function() {
 
@@ skipping 49 matching lines @@
       this.extension_url_ = data.startUrl;
       // TODO(xiyuan): Pre-populate Gaia with data.email (if any).
     },
 
     /**
      * Checks if message comes from the loaded authentication extension.
      * @param e {object} Payload of the received HTML5 message.
      * @type {bool}
      */
     isAuthExtMessage_: function(e) {
-      return this.extension_url_.indexOf(e.origin) == 0;
+      return this.extension_url_ != null &&
+          this.extension_url_.indexOf(e.origin) == 0 &&
+          e.source == $('signin-frame').contentWindow;
     },
 
     /**
      * Event handler that is invoked when HTML5 message is received.
      * @param e {object} Payload of the received HTML5 message.
      */
     onMessage_: function(e) {
       var msg = e.data;
       if (msg.method == 'completeLogin' && this.isAuthExtMessage_(e)) {
         chrome.send('completeLogin', [msg.email, msg.password] );
       }
     }
   };
 
   return {
     GaiaSigninScreen: GaiaSigninScreen
   };
 });