Make unit_tests compile in Mac GN

chrome/browser/apps/app_shim/browser_app_shim.gypi

 # Copyright 2013 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': [
     {
       # This is the part of the Chrome browser process responsible for launching
       # and communicating with app_shim processes on Mac.
+      #
+      # GN version: //chrome/browser/apps/app_shim
       'target_name': 'browser_app_shim',
       'type': 'static_library',
       'dependencies': [
         # Since browser_app_shim and chrome.gyp:browser depend on each other,
         # we omit the dependency on browser here.
         '../content/content.gyp:content_browser',
         '../content/content.gyp:content_common',
       ],
       'sources': [
         'app_shim_handler_mac.cc',
         'app_shim_handler_mac.h',
         'app_shim_host_mac.cc',
         'app_shim_host_mac.h',
         'app_shim_host_manager_mac.h',
         'app_shim_host_manager_mac.mm',
         'extension_app_shim_handler_mac.cc',
         'extension_app_shim_handler_mac.h',
         'unix_domain_socket_acceptor.cc',
         'unix_domain_socket_acceptor.h',
       ],
     },
   ],  # targets
 }