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_