Add browser test for initial languages.

chrome/chrome_tests.gypi

 # 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.
 {
   'variables': {
     'chrome_browser_extensions_test_support_sources': [
       # A list of sources which is shared between different browser tests.
       'browser/apps/app_browsertest_util.cc',
       'browser/apps/app_browsertest_util.h',
       'browser/extensions/browsertest_util.cc',
@@ skipping 82 matching lines @@
       'browser/chrome_service_worker_browsertest.cc',
       'browser/chrome_switches_browsertest.cc',
       'browser/chromeos/accessibility/accessibility_manager_browsertest.cc',
       'browser/chromeos/accessibility/magnification_manager_browsertest.cc',
       'browser/chromeos/accessibility/speech_monitor.cc',
       'browser/chromeos/accessibility/speech_monitor.h',
       'browser/chromeos/accessibility/touch_exploration_controller_browsertest.cc',
       'browser/chromeos/app_mode/kiosk_app_manager_browsertest.cc',
       'browser/chromeos/app_mode/kiosk_app_update_service_browsertest.cc',
       'browser/chromeos/attestation/attestation_policy_browsertest.cc',
+      'browser/chromeos/customization_document_browsertest.cc',
       'browser/chromeos/customization_wallpaper_downloader_browsertest.cc',
       'browser/chromeos/device/input_service_proxy_browsertest.cc',
       'browser/chromeos/drive/drive_integration_service_browsertest.cc',
       'browser/chromeos/drive/drive_notification_manager_factory_browsertest.cc',
       'browser/chromeos/drive/test_util.cc',
       'browser/chromeos/drive/test_util.h',
       'browser/chromeos/extensions/accessibility_features_apitest.cc',
       'browser/chromeos/extensions/echo_private_apitest.cc',
       'browser/chromeos/extensions/file_manager/file_browser_handler_api_test.cc',
       'browser/chromeos/extensions/file_manager/file_manager_private_apitest.cc',
@@ skipping 3125 matching lines @@
             ['enable_webrtc==1', {
               'dependencies': [
                 '../third_party/libjingle/libjingle.gyp:libjingle_webrtc'
               ]
             }],
           ],
         }]
     }],
   ],  # 'conditions'
 }