Revert 31875 to see whether it fixes reliability bot.

ipc/ipc_platform_file.h

-// Copyright (c) 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 IPC_IPC_PLATFORM_FILE_H_
-#define IPC_IPC_PLATFORM_FILE_H_
-
-#include "base/basictypes.h"
-
-#include "base/platform_file.h"
-
-#if defined(OS_POSIX)
-#include "base/file_descriptor_posix.h"
-#endif
-
-namespace IPC {
-
-#if defined(OS_WIN)
-typedef base::PlatformFile PlatformFileForTransit;
-#elif defined(OS_POSIX)
-typedef base::FileDescriptor PlatformFileForTransit;
-#endif
-
-inline base::PlatformFile PlatformFileForTransitToPlatformFile(
-    const PlatformFileForTransit& transit) {
-#if defined(OS_WIN)
-  return transit;
-#elif defined(OS_POSIX)
-  return transit.fd;
-#endif
-}
-
-}  // namespace IPC
-
-#endif  // IPC_IPC_PLATFORM_FILE_H_