Use element.createShadowRoot since WebKitShadowRoot is deprecated.

chrome/chrome_tests.gypi

 # 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.
 {
   'variables' : {
     'pyautolib_sources': [
       'app/chrome_command_ids.h',
       'app/chrome_dll_resource.h',
       'common/automation_constants.h',
       'common/pref_names.cc',
@@ skipping 1017 matching lines @@
         'browser/extensions/options_page_apitest.cc',
         'browser/extensions/page_action_browsertest.cc',
         'browser/extensions/platform_app_browsertest.cc',
         'browser/extensions/platform_app_browsertest_util.cc',
         'browser/extensions/platform_app_browsertest_util.h',
         'browser/extensions/plugin_apitest.cc',
         'browser/extensions/process_management_browsertest.cc',
         'browser/extensions/requirements_checker_browsertest.cc',
         'browser/extensions/sandboxed_pages_apitest.cc',
         'browser/extensions/settings/settings_apitest.cc',
-        'browser/extensions/shadow_dom_apitest.cc',
         'browser/extensions/stubs_apitest.cc',
         'browser/extensions/subscribe_page_action_browsertest.cc',
         'browser/extensions/system/system_apitest.cc',
         'browser/extensions/web_contents_browsertest.cc',
         'browser/extensions/web_view_browsertest.cc',
         'browser/extensions/webstore_standalone_install_browsertest.cc',
         'browser/extensions/window_open_apitest.cc',
         'browser/external_extension_browsertest.cc',
         'browser/fast_shutdown_browsertest.cc',
         'browser/first_run/first_run_browsertest.cc',
@@ skipping 1761 matching lines @@
             'sync_integration_tests.isolate',
           ],
           'sources': [
             'sync_integration_tests.isolate',
           ],
         },
       ],
     }],
   ],  # 'conditions'
 }