Implement image-rendering:pixelated for directly composited images.

Source/platform/graphics/GraphicsLayer.h

Index: Source/platform/graphics/GraphicsLayer.h
diff --git a/Source/platform/graphics/GraphicsLayer.h b/Source/platform/graphics/GraphicsLayer.h
index 56100b38203060aba276fc188a28e86387077ab6..22a427ce4866ecce1d9b198f9b305b300b9d5657 100644
--- a/Source/platform/graphics/GraphicsLayer.h
+++ b/Source/platform/graphics/GraphicsLayer.h
@@ -45,6 +45,7 @@
 #include "public/platform/WebLayerClient.h"
 #include "public/platform/WebLayerScrollClient.h"
 #include "public/platform/WebNinePatchLayer.h"
+#include "third_party/skia/include/core/SkPaint.h"
 #include "wtf/OwnPtr.h"
 #include "wtf/PassOwnPtr.h"
 #include "wtf/Vector.h"
@@ -179,6 +180,8 @@ public:
 
     void setFilters(const FilterOperations&);
 
+    void setFilterLevel(SkPaint::FilterLevel);
+
     // Some GraphicsLayers paint only the foreground or the background content
     void setPaintingPhase(GraphicsLayerPaintingPhase);