Implement a poor man's PostAfterStartupTask() function.

chrome/chrome_browser.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': {
     # All .cc, .h, .m, and .mm files under browser except for:
     # * tests and mocks.
     # * code below browser/chromeos
     # * code below browser/extensions
     # These variables are so the file lists can be shared with the GN build.
     # There are two sections of sources:
     # * "Platform"-based sources (OS, toolkit, etc.)
     # * Feature/directory-based sources (e.g., history, printing)
 
     ### Platform-based sources ###
 
     # The set of sources used on all platforms but iOS that aren't listed in
     # more specific variables below.
     'chrome_browser_non_ios_sources': [
       'browser/about_flags.cc',
       'browser/about_flags.h',
+      'browser/after_startup_task_utils.cc',
+      'browser/after_startup_task_utils.h',
       'browser/android/accessibility/font_size_prefs_android.cc',
       'browser/android/accessibility/font_size_prefs_android.h',
       'browser/android/accessibility_util.cc',
       'browser/android/accessibility_util.h',
       'browser/android/activity_type_id_list.h',
       'browser/android/activity_type_ids.cc',
       'browser/android/activity_type_ids.h',
       'browser/android/appmenu/app_menu_drag_helper.cc',
       'browser/android/appmenu/app_menu_drag_helper.h',
       'browser/android/banners/app_banner_data_fetcher_android.cc',
@@ skipping 3807 matching lines @@
           'variables': {
             'proto_in_dir': 'browser/sync_file_system/drive_backend',
             'proto_out_dir': 'chrome/browser/sync_file_system/drive_backend',
           },
           'includes': [ '../build/protoc.gypi' ]
         },
       ],
     },],
   ],
 }