Add a Record button to the web-app if the host supports video recording.

remoting/webapp/client_screen.js

 // Copyright (c) 2012 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
  * Functions related to the 'client screen' for Chromoting.
  */
 
 'use strict';
@@ skipping 353 matching lines @@
 };
 
 /**
  * Extension message handler.
  *
  * @param {string} type The type of the extension message.
  * @param {string} data The payload of the extension message.
  * @return {boolean} Return true if the extension message was recognized.
  */
 remoting.onExtensionMessage = function(type, data) {
+  if (remoting.clientSession) {
+    return remoting.clientSession.handleExtensionMessage(type, data);
+  }
   return false;
 };
 
 /**
  * Create a session connector if one doesn't already exist.
  */
 remoting.ensureSessionConnector_ = function() {
   if (!remoting.connector) {
     remoting.connector = new remoting.SessionConnector(
         document.getElementById('video-container'),
         remoting.onConnected,
         showConnectError_, remoting.onExtensionMessage);
   }
 };