Move manifest_handler_helpers to //extensions

extensions/extensions.gyp

 # 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': {
     'chromium_code': 1,
   },
   'targets': [
     {
@@ skipping 94 matching lines @@
         'common/id_util.cc',
         'common/id_util.h',
         'common/install_warning.cc',
         'common/install_warning.h',
         'common/manifest.cc',
         'common/manifest.h',
         'common/manifest_constants.cc',
         'common/manifest_constants.h',
         'common/manifest_handler.cc',
         'common/manifest_handler.h',
+        'common/manifest_handler_helpers.cc',
+        'common/manifest_handler_helpers.h',
         'common/manifest_handlers/background_info.cc',
         'common/manifest_handlers/background_info.h',
         'common/manifest_handlers/csp_info.cc',
         'common/manifest_handlers/csp_info.h',
         'common/manifest_handlers/incognito_info.cc',
         'common/manifest_handlers/incognito_info.h',
         'common/manifest_handlers/kiosk_mode_info.cc',
         'common/manifest_handlers/kiosk_mode_info.h',
         'common/manifest_handlers/offline_enabled_info.cc',
         'common/manifest_handlers/offline_enabled_info.h',
@@ skipping 341 matching lines @@
         'common/one_shot_event_unittest.cc',
         'common/permissions/api_permission_set_unittest.cc',
         'common/permissions/manifest_permission_set_unittest.cc',
         'common/url_pattern_set_unittest.cc',
         'common/url_pattern_unittest.cc',
         'common/user_script_unittest.cc',
       ],
     },
   ]
 }