Create base::WorkerPoolJob. Use it for HostResolverImpl and DirectoryLister.

base/base.gypi

 # Copyright (c) 2010 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 302 matching lines @@
           'win/scoped_handle.h',
           'win/scoped_hdc.h',
           'win/scoped_hglobal.h',
           'win/scoped_variant.cc',
           'win/scoped_variant.h',
           'win/windows_version.cc',
           'win/windows_version.h',
           'win_util.cc',
           'win_util.h',
           'worker_pool.h',
+          'worker_pool_job.cc',
+          'worker_pool_job.h',
           'worker_pool_posix.cc',
           'worker_pool_posix.h',
           'worker_pool_win.cc',
           'nix/xdg_util.h',
           'nix/xdg_util.cc',
         ],
         'include_dirs': [
           '..',
         ],
         # These warnings are needed for the files in third_party\dmg_fp.
@@ skipping 409 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',
           ],
         },
       ],
     }],
   ],
 }