Mac Overlays: Add GPU back-pressure

ui/gl/scoped_api.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 UI_GL_SCOPED_API_H_
+#define UI_GL_SCOPED_API_H_
+
+#include "base/basictypes.h"
+#include "ui/gl/gl_export.h"
+
+namespace gfx {
+
+class GLApi;
+
+class GL_EXPORT ScopedSetGLToRealGLApi {
+ public:
+  ScopedSetGLToRealGLApi();
+  ~ScopedSetGLToRealGLApi();
+
+ private:
+  GLApi* old_gl_api_;
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedSetGLToRealGLApi);
+};
+
+}  // namespace gfx
+
+#endif  // UI_GL_SCOPED_API_H_