Implement support for a Context parameter in image filters

src/core/SkDeviceImageFilterProxy.h

Index: src/core/SkDeviceImageFilterProxy.h
diff --git a/src/core/SkDeviceImageFilterProxy.h b/src/core/SkDeviceImageFilterProxy.h
index 6c968e945ee41642c9253d65f9741c3d6ef7990e..5ee563484ee34cf88869863283525b601d59b0f7 100644
--- a/src/core/SkDeviceImageFilterProxy.h
+++ b/src/core/SkDeviceImageFilterProxy.h
@@ -21,9 +21,9 @@ public:
         return fDevice->canHandleImageFilter(filter);
     }
     virtual bool filterImage(const SkImageFilter* filter, const SkBitmap& src,
-                             const SkMatrix& ctm,
+                             const SkImageFilter::Context& ctx,
                              SkBitmap* result, SkIPoint* offset) SK_OVERRIDE {
-        return fDevice->filterImage(filter, src, ctm, result, offset);
+        return fDevice->filterImage(filter, src, ctx, result, offset);
     }
 
 private: