Mac: Other approach for IPCing child task_ts.

base/base.gypi

 # Copyright (c) 2009 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 85 matching lines @@
           'lock.cc',
           'lock.h',
           'lock_impl.h',
           'lock_impl_posix.cc',
           'lock_impl_win.cc',
           'logging.cc',
           'logging_win.cc',
           'logging.h',
           'mac_util.h',
           'mac_util.mm',
+          'mach_ipc_mac.h',
+          'mach_ipc_mac.mm',
           'memory_debug.cc',
           'memory_debug.h',
           'message_loop.cc',
           'message_loop.h',
           'message_pump.h',
           'message_pump_default.cc',
           'message_pump_default.h',
           'message_pump_win.cc',
           'message_pump_win.h',
           'mime_util.h',
@@ skipping 477 matching lines @@
           'configurations': {
             'Common_Base': {
               'msvs_target_platform': 'x64',
             },
           },
         },
       ],
     }],
   ],
 }