Add helpers for CGL types.

ui/gl/scoped_cgl.h

Index: ui/gl/scoped_cgl.h
diff --git a/ui/gl/scoped_cgl.h b/ui/gl/scoped_cgl.h
new file mode 100644
index 0000000000000000000000000000000000000000..81e1e6ea36068c9fddd99123d5a9ac3733e6aa6e
--- /dev/null
+++ b/ui/gl/scoped_cgl.h
@@ -0,0 +1,56 @@
+// 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_SCOPED_CGL_H_
+#define UI_GL_SCOPED_CGL_H_
+
+#include <OpenGL/OpenGL.h>
+
+#include "base/mac/scoped_typeref.h"
+#include "ui/gl/gl_export.h"
+
+namespace base {
+
+template<>
+struct ScopedTypeRefTraits<CGLContextObj> {
+  static void Retain(CGLContextObj object) {
+    CGLRetainContext(object);
+  }
+  static void Release(CGLContextObj object) {
+    CGLReleaseContext(object);
+  }
+};
+
+template<>
+struct ScopedTypeRefTraits<CGLPixelFormatObj> {
+  static void Retain(CGLPixelFormatObj object) {
+    CGLRetainPixelFormat(object);
+  }
+  static void Release(CGLPixelFormatObj object) {
+    CGLReleasePixelFormat(object);
+  }
+};
+
+}  // namespace base
+
+namespace gfx {
+
+class GL_EXPORT ScopedCGLSetCurrentContext {
+ public:
+  explicit 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).
+  base::ScopedTypeRef<CGLContextObj> previous_context_;
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedCGLSetCurrentContext);
+};
+
+}  // namespace gfx
+
+#endif  // UI_GL_SCOPED_CGL_H_