Convert wallpaper picker to v2 app

chrome/browser/resources/chromeos/wallpaper_manager/js/main.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.
 
 /**
  * Global wallpaperManager reference useful for poking at from the console.
 */
 var wallpaperManager;
 
 function init() {
-  window.addEventListener('load', function() {
-      chrome.wallpaperPrivate.minimizeInactiveWindows(); });
-  window.addEventListener('unload', function() {
-      chrome.wallpaperPrivate.restoreMinimizedWindows(); });
   WallpaperManager.initStrings(function() {
     wallpaperManager = new WallpaperManager(document.body);
   });
 }
 
 document.addEventListener('DOMContentLoaded', init);