POSIX: Rewrite IPC's interaction with FileDescriptor

base/file_descriptor_posix.h

 // Copyright (c) 2006-2009 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.
 
 #ifndef BASE_FILE_DESCRIPTOR_POSIX_H_
 #define BASE_FILE_DESCRIPTOR_POSIX_H_
 
 namespace base {
 
 // -----------------------------------------------------------------------------
 // We introduct a special structure for file descriptors in order that we are
 // able to use template specialisation to special-case their handling.
+//
+// WARNING: (Chromium only) There are subtleties to consider if serialising
+// these objects over IPC. See comments in chrome/common/ipc_message_utils.h
+// above the template specialisation for this structure.
 // -----------------------------------------------------------------------------
 struct FileDescriptor {
   FileDescriptor()
       : fd(-1),
         auto_close(false) { }
 
   FileDescriptor(int ifd, bool iauto_close)
       : fd(ifd),
         auto_close(iauto_close) { }
 
   int fd;

[Alpha Left Google, 2009/03/05 20:39:38]

Should this be type base::PlatformFile?

   // If true, this file descriptor should be closed after it has been used. For
   // example an IPC system might interpret this flag as indicating that the
   // file descriptor it has been given should be closed after use.
   bool auto_close;
 };
 
 }  // namespace base
 
 #endif  // BASE_FILE_DESCRIPTOR_POSIX_H_