Extract the element implementation logic to function mods in <webview>.

extensions/renderer/resources/guest_view/extension_options/extension_options.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.
 
 var ExtensionOptionsConstants =
     require('extensionOptionsConstants').ExtensionOptionsConstants;
 var ExtensionOptionsEvents =
     require('extensionOptionsEvents').ExtensionOptionsEvents;
 var GuestViewContainer = require('guestViewContainer').GuestViewContainer;
 
@@ skipping 23 matching lines @@
   // Destroy the old guest if one exists.
   this.guest.destroy();
 
   this.guest.create(this.buildParams(), function() {
     if (!this.guest.getId()) {
       // Fire a createfailed event here rather than in ExtensionOptionsGuest
       // because the guest will not be created, and cannot fire an event.
       var createFailedEvent = new Event('createfailed', { bubbles: true });
       this.dispatchEvent(createFailedEvent);
     } else {
-      this.attachWindow();
+      this.attachWindow$();
     }
   }.bind(this));
 };
 
 GuestViewContainer.registerElement(ExtensionOptionsImpl);
 
 // Exports.
 exports.ExtensionOptionsImpl = ExtensionOptionsImpl;