Implement a second version of the credentials passing API

chrome/browser/resources/gaia_auth/saml_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
  * Script to be injected into SAML provider pages, serving three main purposes:
  * 1. Signal hosting extension that an external page is loaded so that the
  *    UI around it should be changed accordingly;
  * 2. Provide an API via which the SAML provider can pass user credentials to
  *    Chrome OS, allowing the password to be used for encrypting user data and
  *    offline login.
  * 3. Scrape password fields, making the password available to Chrome OS even if
  *    the SAML provider does not support the credential passing API.
  */
 
 (function() {
   function APICallForwarder() {
   }
 
   /**
    * The credential passing API is used by sending messages to the SAML page's
-   * |window| object. This class forwards the calls to a background script via a
-   * |Channel|.
+   * |window| object. This class forwards API calls from the SAML page to a
+   * background script and API responses from the background script to the SAML
+   * page. Communication with the background script occurs via a |Channel|.
    */
   APICallForwarder.prototype = {
     // Channel to which API calls are forwarded.
     channel_: null,
 
     /**
      * Initialize the API call forwarder.
      * @param {!Object} channel Channel to which API calls should be forwarded.
      */
     init: function(channel) {
       this.channel_ = channel;
+      this.channel_.registerMessage('apiResponse',
+                                    this.onAPIResponse_.bind(this));
+
       window.addEventListener('message', this.onMessage_.bind(this));
     },
 
     onMessage_: function(event) {
       if (event.source != window ||
           typeof event.data != 'object' ||
           !event.data.hasOwnProperty('type') ||
           event.data.type != 'gaia_saml_api') {
         return;
       }
-      if (event.data.call.method == 'initialize') {
-        // Respond to the |initialize| call directly.
-        event.source.postMessage({
-            type: 'gaia_saml_api_reply',
-            response: {result: 'initialized', version: 1}}, '/');
-      } else {
-        // Forward all other calls.
-        this.channel_.send({name: 'apiCall', call: event.data.call});
-      }
+      // Forward API calls to the background script.
+      this.channel_.send({name: 'apiCall', call: event.data.call});
+    },
+
+    onAPIResponse_: function(msg) {
+      // Forward API responses to the SAML page.
+      window.postMessage({type: 'gaia_saml_api_reply', response: msg.response},
+                         '/');
     }
   };
 
   /**
    * A class to scrape password from type=password input elements under a given
    * docRoot and send them back via a Channel.
    */
   function PasswordInputScraper() {
   }
 
@@ skipping 103 matching lines @@
       channel.send({name: 'pageLoaded', url: pageURL});
 
       apiCallForwarder = new APICallForwarder();
       apiCallForwarder.init(channel);
 
       passwordScraper = new PasswordInputScraper();
       passwordScraper.init(channel, pageURL, document.documentElement);
     }
   }
 })();