Added JsonMessage to the control channel.

remoting/webapp/client_plugin.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.
 
 /** @suppress {duplicate} */
 var remoting = remoting || {};
 
 /**
  * Interface used for ClientPlugin objects.
  * @interface
@@ skipping 49 matching lines @@
   INJECT_KEY_EVENT: 'injectKeyEvent',
   NOTIFY_CLIENT_DIMENSIONS: 'notifyClientDimensions',
   NOTIFY_CLIENT_RESOLUTION: 'notifyClientResolution',
   ASYNC_PIN: 'asyncPin',
   PAUSE_VIDEO: 'pauseVideo',
   PAUSE_AUDIO: 'pauseAudio',
   REMAP_KEY: 'remapKey',
   SEND_CLIPBOARD_ITEM: 'sendClipboardItem',
   THIRD_PARTY_AUTH: 'thirdPartyAuth',
   TRAP_KEY: 'trapKey',
-  PINLESS_AUTH: 'pinlessAuth'
+  PINLESS_AUTH: 'pinlessAuth',
+  EXTENSION_MESSAGE: 'extensionMessage'
 };
 
 /**
  * @param {remoting.ClientPlugin.Feature} feature The feature to test for.
  * @return {boolean} True if the plugin supports the named feature.
  */
 remoting.ClientPlugin.prototype.hasFeature = function(feature) {};
 
 /**
  * @return {HTMLEmbedElement} HTML element that corresponds to the plugin.
@@ skipping 127 matching lines @@
 
 /**
  * Request pairing with the host for PIN-less authentication.
  *
  * @param {string} clientName The human-readable name of the client.
  * @param {function(string, string):void} onDone, Callback to receive the
  *     client id and shared secret when they are available.
  */
 remoting.ClientPlugin.prototype.requestPairing = function(
     clientName, onDone) {};