Revert of Adds thunks for getting platform handles

mojo/platform_handle/platform_handle_private_thunks.h

-// Copyright 2015 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 MOJO_PLATFORM_HANDLE_PLATFORM_HANDLE_PRIVATE_THUNKS_H_
-#define MOJO_PLATFORM_HANDLE_PLATFORM_HANDLE_PRIVATE_THUNKS_H_
-
-#include <stddef.h>
-
-#include "mojo/platform_handle/platform_handle_functions.h"
-
-#pragma pack(push, 8)
-struct MojoPlatformHandlePrivateThunks {
-  size_t size;  // Should be set to sizeof(PlatformHandleThunks).
-  MojoResult (*CreatePlatformHandleWrapper)(MojoPlatformHandle, MojoHandle*);
-  MojoResult (*ExtractPlatformHandle)(MojoHandle, MojoPlatformHandle*);
-};
-#pragma pack(pop)
-
-inline MojoPlatformHandlePrivateThunks MojoMakePlatformHandlePrivateThunks() {
-  MojoPlatformHandlePrivateThunks system_thunks = {
-      sizeof(MojoPlatformHandlePrivateThunks),
-      MojoCreatePlatformHandleWrapper,
-      MojoExtractPlatformHandle};
-  return system_thunks;
-}
-
-typedef size_t (*MojoSetPlatformHandlePrivateThunksFn)(
-    const struct MojoPlatformHandlePrivateThunks* thunks);
-
-#endif  // MOJO_PLATFORM_HANDLE_PLATFORM_HANDLE_PRIVATE_THUNKS_H_