Add new ExtensionManagement preference

chrome/chrome_tests_unit.gypi

 # Copyright 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': {
     'chrome_unit_tests_sources': [
       '../apps/app_shim/app_shim_host_mac_unittest.cc',
       '../apps/app_shim/extension_app_shim_handler_mac_unittest.cc',
       '../apps/saved_files_service_unittest.cc',
       '../components/autofill/content/renderer/test_password_autofill_agent.cc',
@@ skipping 386 matching lines @@
       'browser/extensions/extension_creator_filter_unittest.cc',
       'browser/extensions/extension_error_controller_unittest.cc',
       'browser/extensions/extension_function_test_utils.cc',
       'browser/extensions/extension_function_test_utils.h',
       'browser/extensions/extension_garbage_collector_unittest.cc',
       'browser/extensions/extension_garbage_collector_chromeos_unittest.cc',
       'browser/extensions/extension_gcm_app_handler_unittest.cc',
       'browser/extensions/extension_icon_manager_unittest.cc',
       'browser/extensions/extension_install_checker_unittest.cc',
       'browser/extensions/extension_install_prompt_unittest.cc',
+      'browser/extensions/extension_management_test_util.cc',
+      'browser/extensions/extension_management_test_util.h',
       'browser/extensions/extension_management_unittest.cc',
       'browser/extensions/extension_message_bubble_controller_unittest.cc',
       'browser/extensions/extension_path_util_unittest.cc',
       'browser/extensions/extension_prefs_unittest.cc',
       'browser/extensions/extension_prefs_unittest.h',
       'browser/extensions/extension_protocols_unittest.cc',
       'browser/extensions/extension_service_test_base.h',
       'browser/extensions/extension_service_test_base.cc',
       'browser/extensions/extension_service_unittest.cc',
       'browser/extensions/extension_special_storage_policy_unittest.cc',
@@ skipping 2464 matching lines @@
               'dependencies': [
                 '../tools/xdisplaycheck/xdisplaycheck.gyp:xdisplaycheck',
               ],
             }],
           ],
         },
       ],
     }],
   ],  # 'conditions'
 }