Make the fuchsia mojo/public repo the source of truth.

mojo/public/platform/native/mgl_signal_sync_point_thunks.c

-// 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/public/platform/native/mgl_signal_sync_point_thunks.h"
-
-#include <assert.h>
-
-#include "mojo/public/platform/native/thunk_export.h"
-
-static struct MGLSignalSyncPointThunks g_signal_sync_point_thunks = {0};
-
-void MGLSignalSyncPoint(uint32_t sync_point,
-                        MGLSignalSyncPointCallback callback,
-                        void* closure) {
-  assert(g_signal_sync_point_thunks.MGLSignalSyncPoint);
-  g_signal_sync_point_thunks.MGLSignalSyncPoint(sync_point, callback, closure);
-}
-
-THUNK_EXPORT size_t MojoSetMGLSignalSyncPointThunks(
-    const struct MGLSignalSyncPointThunks* mgl_signal_sync_point_thunks) {
-  if (mgl_signal_sync_point_thunks->size >= sizeof(g_signal_sync_point_thunks))
-    g_signal_sync_point_thunks = *mgl_signal_sync_point_thunks;
-  return sizeof(g_signal_sync_point_thunks);
-}