Expose SignalSyncPoint through MGL api

mojo/public/c/gpu/MGL/mgl_signal_sync_point.h

Index: mojo/public/c/gpu/MGL/mgl_signal_sync_point.h
diff --git a/mojo/public/c/gpu/MGL/mgl_signal_sync_point.h b/mojo/public/c/gpu/MGL/mgl_signal_sync_point.h
new file mode 100644
index 0000000000000000000000000000000000000000..c7a40dd939ca7db8ee142f3fc76694cc83616d9d
--- /dev/null
+++ b/mojo/public/c/gpu/MGL/mgl_signal_sync_point.h
@@ -0,0 +1,32 @@
+// 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.
+
+// Note: This header should be compilable as C.
+
+#ifndef MOJO_PUBLIC_C_GPU_MGL_MGL_SIGNAL_SYNC_POINT_H_
+#define MOJO_PUBLIC_C_GPU_MGL_MGL_SIGNAL_SYNC_POINT_H_
+
+#include <stdint.h>
+
+#include "mojo/public/c/gpu/MGL/mgl_types.h"
+#include "mojo/public/c/system/types.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef void (*MGLSyncPointCallback)(void* closure);
+
+// MGLSignalSyncPoint signals the given sync point in the current context and
+// invokes |callback| when the service side acknowleges that the sync point has
+// been passed.
+void MGLSignalSyncPoint(uint32_t sync_point,
+                        MGLSignalSyncPointCallback callback,
+                        void* closure);
+
+#ifdef __cplusplus
+}  // extern "C"
+#endif
+
+#endif  // MOJO_PUBLIC_C_GPU_MGL_MGL_SIGNAL_SYNC_POINT_H_