IPC::Message Refactoring: Move POSIX specific bits to PlatformFileAttachment

ipc/ipc.gypi

 # Copyright (c) 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.
 
 {
   'target_defaults': {
     'variables': {
       'ipc_target': 0,
     },
     'target_conditions': [
@@ skipping 70 matching lines @@
           ['>(nacl_untrusted_build)==1', {
             'sources!': [
               'ipc_channel.cc',
               'ipc_channel_posix.cc',
               'unix_domain_socket_util.cc',
             ],
           }],
           ['OS == "win" or OS == "ios"', {
             'sources!': [
               'unix_domain_socket_util.cc',
+              'ipc_platform_file_attachment.cc',
+              'ipc_platform_file_attachment.h',
             ],
           }],
         ],
       }],
     ],
   },
 }