Add best-effort/allow rollback flags on WorkItem.

chrome/chrome_installer.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': {
     'lastchange_path': '../build/util/LASTCHANGE',
     'branding_dir': 'app/theme/<(branding_path_component)',
     'branding_dir_100': 'app/theme/default_100_percent/<(branding_path_component)',
   },
@@ skipping 130 matching lines @@
             'installer/util/run_all_unittests.cc',
             "installer/util/scoped_user_protocol_entry_unittest.cc",
             'installer/util/self_cleaning_temp_dir_unittest.cc',
             'installer/util/set_reg_value_work_item_unittest.cc',
             'installer/util/shell_util_unittest.cc',
             'installer/util/test_app_registration_data.cc',
             'installer/util/test_app_registration_data.h',
             'installer/util/uninstall_metrics_unittest.cc',
             'installer/util/wmi_unittest.cc',
             'installer/util/work_item_list_unittest.cc',
+            'installer/util/work_item_unittest.cc',
           ],
           'msvs_settings': {
             'VCManifestTool': {
               'AdditionalManifestFiles': [
                 '$(ProjectDir)\\installer\\mini_installer\\mini_installer.exe.manifest',
               ],
             },
           },
         },
         {
@@ skipping 967 matching lines @@
             '../build/isolate.gypi',
           ],
           'sources': [
             'setup_unittests.isolate',
           ],
         },
       ],
     }],
   ],
 }