Refactor the bootstrap sandbox process launching integration.

sandbox/mac/sandbox_mac.gypi

 # 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.
 
 {
   'targets': [
     {
       'target_name': 'sandbox',
       'type': '<(component)',
       'sources': [
         'bootstrap_sandbox.cc',
         'bootstrap_sandbox.h',
         'launchd_interception_server.cc',
         'launchd_interception_server.h',
         'mach_message_server.cc',
         'mach_message_server.h',
         'message_server.h',
         'os_compatibility.cc',
         'os_compatibility.h',
         'policy.cc',
         'policy.h',
+        'pre_exec_delegate.cc',
+        'pre_exec_delegate.h',
         'xpc.cc',
         'xpc.h',
         'xpc_message_server.cc',
         'xpc_message_server.h',
       ],
       'dependencies': [
         '../base/base.gyp:base',
       ],
       'include_dirs': [
         '..',
@@ skipping 88 matching lines @@
           'dependencies': [
             'sandbox_mac_unittests',
           ],
           'includes': [ '../../build/isolate.gypi' ],
           'sources': [ '../sandbox_mac_unittests.isolate' ],
         },
       ],
     }],
   ],
 }