Add canFilterMaskGPU & filterMaskGPU to SkMaskFilter

src/core/SkMaskFilter.cpp

Index: src/core/SkMaskFilter.cpp
===================================================================
--- src/core/SkMaskFilter.cpp	(revision 9773)
+++ src/core/SkMaskFilter.cpp	(working copy)
@@ -266,10 +266,23 @@
     return kUnimplemented_FilterReturn;
 }
 
-SkMaskFilter::BlurType SkMaskFilter::asABlur(BlurInfo*) const {
-    return kNone_BlurType;
+bool SkMaskFilter::asNewEffect(GrEffectRef** effect, GrTexture*) const {
+    return false;
 }
 
+bool SkMaskFilter::canFilterMaskGPU(const SkRect& devBounds, 
+                                    const SkIRect& clipBounds,
+                                    const SkMatrix& ctm,
+                                    SkRect* maskRect) const {
+    return false;
+}
+
+bool SkMaskFilter::filterMaskGPU(const SkBitmap& src, 
+                                 const SkRect& maskRect, 
+                                 SkBitmap* result) const {
+    return false;
+}
+
 void SkMaskFilter::computeFastBounds(const SkRect& src, SkRect* dst) const {
     SkMask  srcM, dstM;