Added usefull utility methods to Screen and ScreenContext.

chrome/browser/resources/chromeos/login/login_common.js

 // Copyright 2013 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 Common OOBE controller methods.
  */
 
 <include src="../../login/screen.js"></include>
+<include src="screen_context.js"></include>
 <include src="../user_images_grid.js"></include>
 <include src="apps_menu.js"></include>
 <include src="../../login/bubble.js"></include>
 <include src="../../login/display_manager.js"></include>
 <include src="header_bar.js"></include>
 <include src="network_dropdown.js"></include>
 <include src="oobe_screen_reset.js"></include>
 <include src="oobe_screen_autolaunch.js"></include>
 <include src="oobe_screen_enable_kiosk.js"></include>
 <include src="oobe_screen_terms_of_service.js"></include>
@@ skipping 340 matching lines @@
   cr.ui.login.ResourceLoader.loadAssets(SCREEN_OOBE_ENROLLMENT, function() {
     // This screen is async-loaded so we manually trigger i18n processing.
     i18nTemplate.process($('oauth-enrollment'), loadTimeData);
     // Delayed binding since this isn't defined yet.
     login.OAuthEnrollmentScreen.register();
   });
 
   // Delayed binding since this isn't defined yet.
   cr.ui.Oobe.initialize();
 });