Clean up threading model of external extension providers

base/base.gypi

 # Copyright (c) 2011 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.
 
 {
   'target_defaults': {
     'variables': {
       'base_target': 0,
     },
     'target_conditions': [
@@ skipping 269 matching lines @@
           'tracked_objects.h',
           'tuple.h',
           'utf_offset_string_conversions.cc',
           'utf_offset_string_conversions.h',
           'utf_string_conversion_utils.cc',
           'utf_string_conversion_utils.h',
           'utf_string_conversions.cc',
           'utf_string_conversions.h',
           'values.cc',
           'values.h',
-          'values_util.cc',
-          'values_util.h',
           'version.cc',
           'version.h',
           'vlog.cc',
           'vlog.h',
           'weak_ptr.cc',
           'weak_ptr.h',
           'win/i18n.cc',
           'win/i18n.h',
           'win/object_watcher.cc',
           'win/object_watcher.h',
@@ skipping 427 matching lines @@
             'third_party/xdg_mime/xdgmimemagic.c',
             'third_party/xdg_mime/xdgmimemagic.h',
             'third_party/xdg_mime/xdgmimeparent.c',
             'third_party/xdg_mime/xdgmimeparent.h',
           ],
         },
       ],
     }],
   ],
 }