Use refs for GraphicsContext

third_party/WebKit/Source/platform/Theme.h

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 76 matching lines @@
     virtual LengthSize minimumControlSize(ControlPart, const FontDescription&, float /*zoomFactor*/) const { return LengthSize(Length(0, Fixed), Length(0, Fixed)); }
 
     // Allows the theme to modify the existing padding/border.
     virtual LengthBox controlPadding(ControlPart, const FontDescription&, const LengthBox& zoomedBox, float zoomFactor) const;
     virtual LengthBox controlBorder(ControlPart, const FontDescription&, const LengthBox& zoomedBox, float zoomFactor) const;
 
     // Whether or not whitespace: pre should be forced on always.
     virtual bool controlRequiresPreWhiteSpace(ControlPart) const { return false; }
 
     // Method for painting a control. The rect is in zoomed coordinates.
-    virtual void paint(ControlPart, ControlStates, GraphicsContext*, const IntRect& /*zoomedRect*/, float /*zoomFactor*/, ScrollableArea*) const { }
+    virtual void paint(ControlPart, ControlStates, GraphicsContext&, const IntRect& /*zoomedRect*/, float /*zoomFactor*/, ScrollableArea*) const { }
 
     // Add visual overflow (e.g., the check on an OS X checkbox). The rect passed in is in zoomed coordinates so
     // the inflation should take that into account and make sure the inflation amount is also scaled by the zoomFactor.
     virtual void addVisualOverflow(ControlPart, ControlStates, float zoomFactor, IntRect& borderBox) const { }
 
 private:
     mutable Color m_activeSelectionColor;
     mutable Color m_inactiveSelectionColor;
 };
 
 PLATFORM_EXPORT Theme* platformTheme();
 
 } // namespace blink
 
 #endif // Theme_h