Add helpers for CGL types.

ui/gl/cgl_util.h

+// Copyright 2014 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_CGL_UTIL_H_
+#define UI_GL_CGL_UTIL_H_
+
+#include <OpenGL/OpenGL.h>
+
+#include "base/mac/scoped_typeref.h"
+#include "ui/gl/gl_export.h"
+
+namespace gfx {
+
+typedef base::ScopedTypeRef<
+    CGLContextObj,
+    CGLContextObj,
+    CGLRetainContext,
+    CGLReleaseContext>
+        ScopedCGLContextObjRef;
+
+typedef base::ScopedTypeRef<
+    CGLPixelFormatObj,
+    CGLPixelFormatObj,
+    CGLRetainPixelFormat,
+    CGLReleasePixelFormat>
+        ScopedCGLPixelFormatObjRef;
+
+class GL_EXPORT ScopedCGLSetCurrentContext {
+ public:
+  ScopedCGLSetCurrentContext(CGLContextObj context);
+  ~ScopedCGLSetCurrentContext();
+ private:
+  // Note that if a context is destroyed when it is current, then the current
+  // context is changed to NULL. Take out a reference on |previous_context_| to
+  // preserve this behavior (when this falls out of scope, |previous_context_|
+  // will be made current, then released, so NULL will be current if that
+  // release destroys the context).
+  ScopedCGLContextObjRef previous_context_;
+};
+
+}  // namespace gfx
+
+#endif  // UI_GL_CGL_UTIL_H_