ChromeOS Gaia: send message 'handshake' to Gaia to establish connection channel

chrome/browser/resources/gaia_auth_host/authenticator.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.
 
 /**
  * @fileoverview An UI component to authenciate to Chrome. The component hosts
  * IdP web pages in a webview. A client who is interested in monitoring
  * authentication events should pass a listener object of type
  * cr.login.GaiaAuthHost.Listener as defined in this file. After initialization,
  * call {@code load} to start the authentication flow.
@@ skipping 314 matching lines @@
   };
 
   /**
    * Invoked when a new document is loaded.
    * @private
    */
   Authenticator.prototype.onContentLoad_ = function(e) {
     // Posts a message to IdP pages to initiate communication.
     var currentUrl = this.webview_.src;
     if (currentUrl.lastIndexOf(this.idpOrigin_) == 0) {
-      this.webview_.contentWindow.postMessage({}, currentUrl);
+      var msg = {
+        'method': 'handshake'
+      };
+      this.webview_.contentWindow.postMessage(msg, currentUrl);
     }
   };
 
   /**
    * Invoked when the webview finishes loading a page.
    * @private
    */
   Authenticator.prototype.onLoadStop_ = function(e) {
     if (!this.loaded_) {
       this.loaded_ = true;
@@ skipping 20 matching lines @@
   Authenticator.AuthFlow = AuthFlow;
   Authenticator.AuthMode = AuthMode;
   Authenticator.SUPPORTED_PARAMS = SUPPORTED_PARAMS;
 
   return {
     // TODO(guohui, xiyuan): Rename GaiaAuthHost to Authenticator once the old
     // iframe-based flow is deprecated.
     GaiaAuthHost: Authenticator
   };
 });