Remove openglui embedder code

runtime/embedders/openglui/common/extension.h

Index: runtime/embedders/openglui/common/extension.h
diff --git a/runtime/embedders/openglui/common/extension.h b/runtime/embedders/openglui/common/extension.h
deleted file mode 100644
index a13413ef4f8c02a8c2ef52265f503076e73e3cd0..0000000000000000000000000000000000000000
--- a/runtime/embedders/openglui/common/extension.h
+++ /dev/null
@@ -1,20 +0,0 @@
-// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-#ifndef EMBEDDERS_OPENGLUI_COMMON_EXTENSION_H_
-#define EMBEDDERS_OPENGLUI_COMMON_EXTENSION_H_
-
-#include "include/dart_api.h"
-
-Dart_NativeFunction ResolveName(Dart_Handle name, int argc);
-
-extern int32_t PlayBackgroundSound(const char* path);
-extern void StopBackgroundSound();
-extern int32_t LoadSoundSample(const char* path);
-extern int32_t PlaySoundSample(const char* path);
-extern int32_t Init2DGraphics();
-
-
-#endif  // EMBEDDERS_OPENGLUI_COMMON_EXTENSION_H_
-