Use SkLayerDrawLooper::Builder to construct SkLayerDrawLooper.

Source/platform/graphics/GraphicsContext.h

 /*
  * Copyright (C) 2003, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2008-2009 Torch Mobile, Inc.
  * Copyright (C) 2013 Google 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.
@@ skipping 302 matching lines @@
     PassRefPtr<DisplayList> endRecording();
 
     bool hasShadow() const;
     void setShadow(const FloatSize& offset, float blur, const Color&,
         DrawLooper::ShadowTransformMode = DrawLooper::ShadowRespectsTransforms,
         DrawLooper::ShadowAlphaMode = DrawLooper::ShadowRespectsAlpha);
     void clearShadow() { clearDrawLooper(); }
 
     // It is assumed that this draw looper is used only for shadows
     // (i.e. a draw looper is set if and only if there is a shadow).
-    void setDrawLooper(const DrawLooper&);
+    void setDrawLooper(DrawLooper&);

[jbroman, 2014/02/24 15:23:33]

Passing a non-const reference here seems odd. Especially now that the underlying
draw loopers are becoming immutable, it would be nice to pass something
immutable here too.

     void clearDrawLooper();
 
     void drawFocusRing(const Vector<IntRect>&, int width, int offset, const Color&);
     void drawFocusRing(const Path&, int width, int offset, const Color&);
 
     enum Edge {
         NoEdge = 0,
         TopEdge = 1 << 1,
         RightEdge = 1 << 2,
         BottomEdge = 1 << 3,
@@ skipping 175 matching lines @@
     // FIXME: Make this go away: crbug.com/236892
     bool m_updatingControlTints : 1;
     bool m_accelerated : 1;
     bool m_isCertainlyOpaque : 1;
     bool m_printing : 1;
 };
 
 } // namespace WebCore
 
 #endif // GraphicsContext_h