Use element.createShadowRoot since WebKitShadowRoot is deprecated.

chrome/test/data/extensions/api_test/shadow_dom/background.js

Index: chrome/test/data/extensions/api_test/shadow_dom/background.js
diff --git a/chrome/test/data/extensions/api_test/shadow_dom/background.js b/chrome/test/data/extensions/api_test/shadow_dom/background.js
deleted file mode 100644
index e2e4428e80859fa7d6c99da7cc948ad33603c654..0000000000000000000000000000000000000000
--- a/chrome/test/data/extensions/api_test/shadow_dom/background.js
+++ /dev/null
@@ -1,16 +0,0 @@
-// 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.test.runTests([
-  function currentWindow() {
-    chrome.test.assertTrue('WebKitShadowRoot' in window);
-    chrome.test.succeed();
-  },
-
-  function newWindow() {
-    var w = window.open('empty.html');
-    chrome.test.assertTrue('WebKitShadowRoot' in w);
-    chrome.test.succeed();
-  }
-]);