Implement inline signin with iframe

chrome/browser/resources/gaia_auth/desktop_injected.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.
 
 /**
  * @fileoverview Code injected into Gaia sign in page for inline sign in flow.
  * On load stop, it receives a message from the embedder extension with a
  * JavaScript reference to the embedder window. Then upon submit of the sign
  * in form, it posts the username and password to the embedder window.
  * Prototype Only.
  */
 
 (function() {
-  var extWindow;
+  var $ = function(id) { return document.getElementById(id); };
 
-  var $ = function(id) { return document.getElementById(id); };
   var gaiaLoginForm = $('gaia_loginform');
-
-  var onMessage = function(e) {
-    extWindow = e.source;
-  };
-  window.addEventListener('message', onMessage);
+  if (!gaiaLoginForm) {
+    return;
+  }
 
   var onLoginSubmit = function(e) {
-    if (!extWindow) {
-      console.log('ERROR: no initial message received from the gaia ext');
-      e.preventDefault();
-      return;
-    }
-
     var checkboxElement = $('advanced-box');
     var chooseWhatToSync = checkboxElement && checkboxElement.checked;
     var msg = {method: 'attemptLogin',
                email: gaiaLoginForm['Email'].value,
                password: gaiaLoginForm['Passwd'].value,
                attemptToken: new Date().getTime(),
                chooseWhatToSync: chooseWhatToSync};
 
-    extWindow.postMessage(msg, 'chrome://chrome-signin');
+    window.parent.postMessage(
+        msg, 'chrome-extension://mfffpogegjflfpflabcdkioaeobkgjik');
     console.log('Credentials sent');
 
     return;
   };
   // Overrides the submit handler for the gaia login form.
   gaiaLoginForm.onsubmit = onLoginSubmit;
 })();