Remove chrome.windows.* support for platform apps.

chrome/test/data/extensions/platform_apps/context_menu/test.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.
 
 chrome.experimental.app.onLaunched.addListener(function() {
   chrome.contextMenus.create({
         id: 'id1',
         title: 'Extension Item 1',
       },
       function() {
-        chrome.windows.create({
-            url: 'main.html',
-            type: 'shell'
-        });
+        chrome.appWindow.create('main.html', {}, function() {});
       });
 });