Convert wallpaper picker to v2 app

chrome/browser/resources/chromeos/wallpaper_manager/js/event_page.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.
+
+var WALLPAPER_PICKER_WIDTH = 550;
+var WALLPAPER_PICKER_HEIGHT = 420;
+
+var wallpaperPickerWindow;
+
+chrome.app.runtime.onLaunched.addListener(function() {
+  if (wallpaperPickerWindow && !wallpaperPickerWindow.contentWindow.closed) {
+    wallpaperPickerWindow.focus();
+    return;
+  }
+
+  chrome.app.window.create('main.html', {
+    frame: 'chrome',
+    width: WALLPAPER_PICKER_WIDTH,
+    height: WALLPAPER_PICKER_HEIGHT
+  }, function(w) { wallpaperPickerWindow = w; });
+});