Don't make classes derive from ChildProcessHost, and instead have them use it through composition...

chrome/chrome.gyp

 # 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.
 {
   'variables': {
     'chromium_code': 1,
 
     'variables': {
       'version_py_path': 'tools/build/version.py',
       'version_path': 'VERSION',
@@ skipping 586 matching lines @@
         '../base/base.gyp:base',
         '../jingle/jingle.gyp:notifier',
         '../net/net.gyp:net',
         '../printing/printing.gyp:printing',
         '../skia/skia.gyp:skia',
         '../third_party/libjingle/libjingle.gyp:libjingle',
       ],
       'sources': [
         'service/chrome_service_application_mac.h',
         'service/chrome_service_application_mac.mm',
-        'service/service_child_process_host.cc',
-        'service/service_child_process_host.h',
         'service/service_ipc_server.cc',
         'service/service_ipc_server.h',
         'service/service_main.cc',
         'service/service_process.cc',
         'service/service_process.h',
         'service/service_process_prefs.cc',
         'service/service_process_prefs.h',
         'service/service_utility_process_host.cc',
         'service/service_utility_process_host.h',
         'service/cloud_print/cloud_print_auth.cc',
@@ skipping 682 matching lines @@
           'configurations': {
             'Common_Base': {
               'msvs_target_platform': 'x64',
             },
           },
         },
       ]},  # 'targets'
     ],  # OS=="win"
   ],  # 'conditions'
 }