Write an extension-upgrade browsertest to verify the fix for http://crbug.com/178542.

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 1390 matching lines @@
         'browser/extensions/extension_fileapi_apitest.cc',
         'browser/extensions/extension_functional_browsertest.cc',
         'browser/extensions/extension_function_test_utils.cc',
         'browser/extensions/extension_function_test_utils.h',
         'browser/extensions/extension_geolocation_apitest.cc',
         'browser/extensions/extension_get_views_apitest.cc',
         'browser/extensions/extension_icon_source_apitest.cc',
         'browser/extensions/extension_incognito_apitest.cc',
         'browser/extensions/extension_install_ui_browsertest.cc',
         'browser/extensions/extension_javascript_url_apitest.cc',
+        'browser/extensions/extension_loading_browsertest.cc',
         'browser/extensions/extension_messages_apitest.cc',
         'browser/extensions/extension_override_apitest.cc',
         'browser/extensions/extension_resource_request_policy_apitest.cc',
         'browser/extensions/extension_startup_browsertest.cc',
         'browser/extensions/extension_storage_apitest.cc',
         'browser/extensions/extension_tabs_apitest.cc',
         'browser/extensions/extension_test_message_listener.cc',
         'browser/extensions/extension_test_message_listener.h',
         'browser/extensions/extension_toolbar_model_browsertest.cc',
         'browser/extensions/extension_url_rewrite_browsertest.cc',
@@ skipping 1967 matching lines @@
               # more details.
               'DebugInformationFormat': '3',
               'ProgramDataBaseFileName': '<(PRODUCT_DIR)/browser_tests.exe.pdb',
             },
           },
         },
       ],
     }],
   ],  # 'conditions'
 }