Refactoring DrawLooper so that it can apply shadow effects as skia image filters

Source/core/platform/graphics/GraphicsContextState.h

 // 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:
 //
 //    * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
 //    * Redistributions in binary form must reproduce the above
 // copyright notice, this list of conditions and the following disclaimer
@@ skipping 98 matching lines @@
     // Stroke.
     StrokeData m_strokeData;
 
     // Fill.
     Color m_fillColor;
     WindRule m_fillRule;
     RefPtr<Gradient> m_fillGradient;
     RefPtr<Pattern> m_fillPattern;
 
     // Shadow. (This will need tweaking if we use draw loopers for other things.)
-    RefPtr<SkDrawLooper> m_looper;
+    RefPtr<DrawLooper> m_looper;
 
     // Text. (See TextModeFill & friends.)
     TextDrawingModeFlags m_textDrawingMode;
 
     // Common shader state.
     float m_alpha;
     SkXfermode::Mode m_xferMode;
 
     // Compositing control, for the CSS and Canvas compositing spec.
     CompositeOperator m_compositeOperator;
     BlendMode m_blendMode;
 
     // If non-empty, the current State is clipped to this image.
     SkBitmap m_imageBufferClip;
 
     // If m_imageBufferClip is non-empty, this is the region the image is clipped to.
     SkRect m_clip;
 
     // Image interpolation control.
     InterpolationQuality m_interpolationQuality;
 
     bool m_shouldAntialias : 1;
     bool m_shouldSmoothFonts : 1;
 };
 
 } // namespace WebCore
 
 #endif // GraphicsContextState_h