[Chromoting] Add ability to enable/disable GDrive support per-app in gyp.

remoting/webapp/app_remoting/js/ar_main.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.
 
 'use strict';
 
 /** @suppress {duplicate} */
 var remoting = remoting || {};
 
 /**
  * Entry point ('load' handler) for App Remoting webapp.
  */
 remoting.startAppRemoting = function() {
-  remoting.app = new remoting.Application();
+  remoting.app = new remoting.Application(remoting.app_capabilities());
   var app_remoting = new remoting.AppRemoting(remoting.app);
   remoting.app.start();
 };
 
 window.addEventListener('load', remoting.startAppRemoting, false);