Add a SigninAllowed policy.

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' : {
     'pyautolib_sources': [
       'app/chrome_command_ids.h',
       'app/chrome_dll_resource.h',
       'common/automation_constants.h',
       'common/pref_names.cc',
@@ skipping 1359 matching lines @@
         'browser/ui/webui/bookmarks_ui_browsertest.cc',
         'browser/ui/webui/chrome_url_data_manager_browsertest.cc',
         'browser/ui/webui/constrained_web_dialog_ui_browsertest.cc',
         'browser/ui/webui/downloads_dom_handler_browsertest.cc',
         'browser/ui/webui/extensions/extension_settings_browsertest.js',
         'browser/ui/webui/help/help_browsertest.js',
         'browser/ui/webui/inspect_ui_browsertest.cc',
         'browser/ui/webui/net_internals/net_internals_ui_browsertest.cc',
         'browser/ui/webui/net_internals/net_internals_ui_browsertest.h',
         'browser/ui/webui/ntp/most_visited_browsertest.cc',
+        'browser/ui/webui/ntp/new_tab_page_sync_handler_browsertest.cc',
         'browser/ui/webui/ntp/new_tab_ui_browsertest.cc',
         'browser/ui/webui/options/autofill_options_browsertest.js',
         'browser/ui/webui/options/browser_options_browsertest.js',
         'browser/ui/webui/options/certificate_manager_browsertest.js',
         'browser/ui/webui/options/chromeos/guest_mode_options_ui_browsertest.cc',
         'browser/ui/webui/options/content_options_browsertest.js',
         'browser/ui/webui/options/content_settings_exception_area_browsertest.js',
         'browser/ui/webui/options/cookies_view_browsertest.js',
         'browser/ui/webui/options/edit_dictionary_browsertest.js',
         'browser/ui/webui/options/font_settings_browsertest.js',
@@ skipping 1714 matching lines @@
               # more details.
               'DebugInformationFormat': '3',
               'ProgramDataBaseFileName': '<(PRODUCT_DIR)/browser_tests.exe.pdb',
             },
           },
         },
       ],
     }],
   ],  # 'conditions'
 }