Fix GN bootstrap

tools/gn/bootstrap/bootstrap.py

 #!/usr/bin/env python
 # Copyright 2014 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.
 
 # This file isn't officially supported by the Chromium project. It's maintained
 # on a best-effort basis by volunteers, so some things may be broken from time
 # to time. If you encounter errors, it's most often due to files in base that
 # have been added or moved since somebody last tried this script. Generally
 # such errors are easy to diagnose.
@@ skipping 469 matching lines @@
       'base/strings/string_util.cc',
       'base/strings/string_util_constants.cc',
       'base/strings/stringprintf.cc',
       'base/strings/utf_string_conversion_utils.cc',
       'base/strings/utf_string_conversions.cc',
       'base/synchronization/atomic_flag.cc',
       'base/synchronization/lock.cc',
       'base/sys_info.cc',
       'base/task_runner.cc',
       'base/task_scheduler/delayed_task_manager.cc',
+      'base/task_scheduler/environment_config.cc',
       'base/task_scheduler/post_task.cc',
       'base/task_scheduler/priority_queue.cc',
       'base/task_scheduler/scheduler_lock_impl.cc',
       'base/task_scheduler/scheduler_single_thread_task_runner_manager.cc',
       'base/task_scheduler/scheduler_worker.cc',
       'base/task_scheduler/scheduler_worker_pool_impl.cc',
       'base/task_scheduler/scheduler_worker_pool_params.cc',
       'base/task_scheduler/scheduler_worker_stack.cc',
       'base/task_scheduler/scoped_set_task_priority_for_current_thread.cc',
       'base/task_scheduler/sequence.cc',
@@ skipping 318 matching lines @@
     cmd.append('-v')
   cmd.append('gn')
   check_call(cmd)
 
   if not options.debug and not is_win:
     check_call(['strip', os.path.join(build_dir, 'gn')])
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))