Consistently decorate pref values sent to the settings UI code

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 2949 matching lines @@
         'browser/ui/webui/options2/chromeos/guest_mode_options_ui_browsertest.cc',
         'browser/ui/webui/options2/content_options_browsertest.js',
         'browser/ui/webui/options2/content_settings_exception_area_browsertest.js',
         'browser/ui/webui/options2/cookies_view_browsertest.js',
         'browser/ui/webui/options2/font_settings_browsertest.js',
         'browser/ui/webui/options2/language_options_browsertest.js',
         'browser/ui/webui/options2/options_browsertest.js',
         'browser/ui/webui/options2/options_ui_browsertest.cc',
         'browser/ui/webui/options2/options_ui_browsertest.h',
         'browser/ui/webui/options2/password_manager_browsertest.js',
+        'browser/ui/webui/options2/preferences_browsertest.cc',
+        'browser/ui/webui/options2/preferences_browsertest.h',
         'browser/ui/webui/options2/search_engine_manager_browsertest.js',
         'browser/ui/webui/print_preview/print_preview_ui_browsertest.cc',
         'browser/ui/webui/sync_setup_browsertest.js',
         'browser/ui/webui/test_web_dialog_delegate.cc',
         'browser/ui/webui/test_web_dialog_delegate.h',
         'browser/ui/webui/web_ui_browsertest.cc',
         'browser/ui/webui/web_ui_browsertest.h',
         'browser/ui/webui/web_ui_test_handler.cc',
         'browser/ui/webui/web_ui_test_handler.h',
         'browser/unload_browsertest.cc',
@@ skipping 1687 matching lines @@
                 '--result', '<@(_outputs)',
                 '--isolate', 'browser_tests.isolate',
               ],
             },
           ],
         },
       ],
     }],
   ],  # 'conditions'
 }