Adds thunks for getting platform handles

mojo/runner/platform_handle_impl.cc

+// 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.
+
+#include "mojo/platform_handle/platform_handle.h"
+#include "third_party/mojo/src/mojo/edk/embedder/embedder.h"
+
+extern "C" {
+
+MojoResult MojoCreatePlatformHandleWrapper(MojoPlatformHandle platform_handle,
+                                           MojoHandle* wrapper) {
+  mojo::embedder::PlatformHandle platform_handle_wrapper(platform_handle);
+  mojo::embedder::ScopedPlatformHandle scoped_platform_handle(
+      platform_handle_wrapper);
+  return mojo::embedder::CreatePlatformHandleWrapper(
+      scoped_platform_handle.Pass(), wrapper);
+}
+
+MojoResult MojoExtractPlatformHandle(MojoHandle wrapper,
+                                     MojoPlatformHandle* platform_handle) {
+  mojo::embedder::ScopedPlatformHandle scoped_platform_handle;
+  MojoResult result = mojo::embedder::PassWrappedPlatformHandle(
+      wrapper, &scoped_platform_handle);
+  if (result != MOJO_RESULT_OK)
+    return result;
+
+  DCHECK(scoped_platform_handle.is_valid());
+#if defined(OS_POSIX)
+  *platform_handle = scoped_platform_handle.release().fd;
+#elif defined(OS_WIN)
+  *platform_handle = scoped_platform_handle.release().handle;
+#else
+#error "Platform not yet supported."
+#endif
+  return MOJO_RESULT_OK;
+}
+
+}  // extern "C"