[Chromoting] Move shared webapp JS files from crd/js -> base/js

remoting/webapp/base/js/client_plugin_impl.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.
 
 /**
  * @fileoverview
  * Class that wraps low-level details of interacting with the client plugin.
  *
  * This abstracts a <embed> element and controls the plugin which does
  * the actual remoting work. It also handles differences between
@@ skipping 891 matching lines @@
 remoting.DefaultClientPluginFactory.prototype.preloadPlugin = function() {
   if (remoting.settings.CLIENT_PLUGIN_TYPE != 'pnacl') {
     return;
   }
 
   var plugin = remoting.ClientPluginImpl.createPluginElement_();
   plugin.addEventListener(
       'loadend', function() { document.body.removeChild(plugin); }, false);
   document.body.appendChild(plugin);
 };