Use refs for GraphicsContext

third_party/WebKit/Source/platform/graphics/GeneratedImage.h

 /*
  * Copyright (C) 2008 Apple Computer, 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 31 matching lines @@
     void computeIntrinsicDimensions(Length& intrinsicWidth, Length& intrinsicHeight, FloatSize& intrinsicRatio) override;
 
     IntSize size() const override { return m_size; }
 
     // Assume that generated content has no decoded data we need to worry about
     void destroyDecodedData(bool) override { }
 
     PassRefPtr<SkImage> imageForCurrentFrame() override;
 
 protected:
-    void drawPattern(GraphicsContext*, const FloatRect&,
+    void drawPattern(GraphicsContext&, const FloatRect&,
         const FloatSize&, const FloatPoint&, SkXfermode::Mode,
         const FloatRect&, const FloatSize& repeatSpacing) final;
 
     // FIXME: Implement this to be less conservative.
     bool currentFrameKnownToBeOpaque(MetadataMode = UseCurrentMetadata) override { return false; }
 
     GeneratedImage(const IntSize& size) : m_size(size) { }
 
-    virtual void drawTile(GraphicsContext*, const FloatRect&) = 0;
+    virtual void drawTile(GraphicsContext&, const FloatRect&) = 0;
 
     IntSize m_size;
 };
 
 } // namespace blink
 
 #endif