Move ProtocolExtensionManager from SessionConnector into its own class

remoting/webapp/crd/js/desktop_remoting.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
  * This class implements the functionality that is specific to desktop
  * remoting ("Chromoting" or CRD).
  */
 
@@ skipping 165 matching lines @@
 
   this.connectedView_ = new remoting.DesktopConnectedView(
       document.getElementById('client-container'), connectionInfo);
 
   // By default, under ChromeOS, remap the right Control key to the right
   // Win / Cmd key.
   if (remoting.platformIsChromeOS()) {
     connectionInfo.plugin().setRemapKeys('0x0700e4>0x0700e7');
   }
 
+  var plugin = connectionInfo.plugin();
   if (remoting.app.getConnectionMode() === remoting.Application.Mode.ME2ME) {
     if (remoting.app.hasCapability(remoting.ClientSession.Capability.CAST)) {
-      this.sessionConnector_.registerProtocolExtension(
-          new remoting.CastExtensionHandler());
+      plugin.extensions().register(new remoting.CastExtensionHandler());
     }
-    this.sessionConnector_.registerProtocolExtension(
-        new remoting.GnubbyAuthHandler());
+    plugin.extensions().register(new remoting.GnubbyAuthHandler());
   }
   if (connectionInfo.session().hasCapability(
           remoting.ClientSession.Capability.VIDEO_RECORDER)) {
     var recorder = new remoting.VideoFrameRecorder();
-    this.sessionConnector_.registerProtocolExtension(recorder);
+    plugin.extensions().register(recorder);
     this.connectedView_.setVideoFrameRecorder(recorder);
   }
 
   if (remoting.pairingRequested) {
     var that = this;
     /**
      * @param {string} clientId
      * @param {string} sharedSecret
      */
     var onPairingComplete = function(clientId, sharedSecret) {
@@ skipping 165 matching lines @@
 
 /**
  * Entry-point for It2Me connections.
  *
  * @private
  */
 remoting.DesktopRemoting.prototype.connectIt2Me_ = function() {
   var flow = new remoting.It2MeConnectFlow(this.sessionConnector_);
   flow.start();
 };