Move ProtocolExtensionManager from SessionConnector into its own class

remoting/webapp/crd/js/client_plugin.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
  * Interface abstracting the ClientPlugin functionality.
  */
 
 'use strict';
 
 /** @suppress {duplicate} */
 var remoting = remoting || {};
 
 /**
  * @interface
  * @extends {base.Disposable}
  */
 remoting.ClientPlugin = function() {};
 
 /**
  * @return {remoting.HostDesktop}
  */
 remoting.ClientPlugin.prototype.hostDesktop = function() {};
 
 /**
+ * @return {remoting.ProtocolExtensionManager}
+ */
+remoting.ClientPlugin.prototype.extensions = function() {};
+
+/**
  * @return {HTMLElement} The DOM element representing the remote session.
  */
 remoting.ClientPlugin.prototype.element = function() {};
 
 /**
  * @param {function(boolean):void} onDone Completion callback.
  */
 remoting.ClientPlugin.prototype.initialize = function(onDone) {};
 
 /**
@@ skipping 187 matching lines @@
     function(ready) {};
 
 /**
  * @param {!Array<string>} capabilities The set of capabilities negotiated
  *     between the client and host.
  */
 remoting.ClientPlugin.ConnectionEventHandler.prototype.onSetCapabilities =
     function(capabilities) {};
 
 /**
- * @param {string} type
- * @param {string} data
- */
-remoting.ClientPlugin.ConnectionEventHandler.prototype.onExtensionMessage =
-    function(type, data) {};
-
-
-/**
  * @interface
  */
 remoting.ClientPluginFactory = function() {};
 
 /**
  * @param {Element} container The container for the embed element.
  * @param {Array<string>} requiredCapabilities
  * @return {remoting.ClientPlugin} A new client plugin instance.
  */
 remoting.ClientPluginFactory.prototype.createPlugin =
     function(container, requiredCapabilities) {};
 
 /**
  * Preload the plugin to make instantiation faster when the user tries
  * to connect.
  */
 remoting.ClientPluginFactory.prototype.preloadPlugin = function() {};
 
 /**
  * @type {remoting.ClientPluginFactory}
  */
 remoting.ClientPlugin.factory = null;