Download the host components when user tries to enable Me2Me host.

remoting/webapp/host_controller.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.
 
 'use strict';
 
 /** @suppress {duplicate} */
 var remoting = remoting || {};
 
 /** @constructor */
 remoting.HostController = function() {
   /** @return {remoting.HostPlugin} */
   var createPluginForMe2Me = function() {
     var plugin = remoting.HostSession.createPlugin();
     /** @type {HTMLElement} @private */
     var container = document.getElementById('daemon-plugin-container');
     container.appendChild(plugin);
+    if (plugin.getDaemonState === undefined) {

[weitao, 2014/01/31 18:37:11]

Remoting.js uses a different way of detecting the plugin:

plugin.hasOwnProperty('REQUESTED_ACCESS_CODE');

Which is the preferred way?

I recommend having an isNpapiPluginSupported() function in remoting.js that
unifies all these checks.

[Sergey Ulanov, 2014/01/31 23:34:17]

It's essentially the same, except we are using different properties.
hasOwnProperty() is slightly better because it doesn't look at the object's
prototype.
I don't think it's worth worrying about it much. Hopefully we can remove all
NPAPI-related code soon. I'm working another CL to integrate download in It2Me
flow - I'll need to refactor plugin loading for It2Me, so I'll make sure the
plugin loading code is shared..

+      container.removeChild(plugin);
+      return null;
+    }
     return plugin;
   };
 
   /** @type {remoting.HostDispatcher} @private */
   this.hostDispatcher_ = new remoting.HostDispatcher(createPluginForMe2Me);
 
   /** @param {string} version */
   var printVersion = function(version) {
     if (version == '') {
       console.log('Host not installed.');
@@ skipping 439 matching lines @@
  * @param {function(remoting.Error):void} onError Error callback.
  * @return {void}
  */
 remoting.HostController.prototype.clearPairedClients = function(
     onDone, onError) {
   this.hostDispatcher_.clearPairedClients(onDone, onError);
 };
 
 /** @type {remoting.HostController} */
 remoting.hostController = null;