Add and use gfx::ScopedNSGraphicsContextState (ui/gfx/scoped_ns_graphics_context_state_mac.h).

ui/gfx/scoped_ns_graphics_context_save_gstate_mac.h

+// Copyright (c) 2011 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_GFX_SCOPED_NS_GRAPHICS_CONTEXT_SAVE_GSTATE_MAC_H_
+#define UI_GFX_SCOPED_NS_GRAPHICS_CONTEXT_SAVE_GSTATE_MAC_H_
+
+#include "base/basictypes.h"
+#include "base/memory/scoped_nsobject.h"
+
+@class NSGraphicsContext;
+
+namespace gfx {
+
+// What this class does should be self-evident and self-documenting.
+class ScopedNSGraphicsContextSaveGState {
+ public:
+  // If |context| is nil, it will use the |+currentContext|.
+  explicit ScopedNSGraphicsContextSaveGState(NSGraphicsContext* context = nil);
+  ~ScopedNSGraphicsContextSaveGState();
+
+ private:
+  scoped_nsobject<NSGraphicsContext> context_;
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedNSGraphicsContextSaveGState);
+};
+
+}  // namespace gfx
+
+#endif  // UI_GFX_SCOPED_NS_GRAPHICS_CONTEXT_SAVE_GSTATE_MAC_H_