switch maskfilters to sk_sp

gm/drawlooper.cpp

Index: gm/drawlooper.cpp
diff --git a/gm/drawlooper.cpp b/gm/drawlooper.cpp
index 7ee774720821bf57d5ddc34b1a877d39f915d870..019566e30f46b245ea0bebd05046a94c57194e34 100644
--- a/gm/drawlooper.cpp
+++ b/gm/drawlooper.cpp
@@ -82,9 +82,8 @@ private:
             paint->setStyle(gParams[i].fStyle);
             paint->setStrokeWidth(gParams[i].fWidth);
             if (gParams[i].fBlur > 0) {
-                SkMaskFilter* mf = SkBlurMaskFilter::Create(kNormal_SkBlurStyle,
-                                         SkBlurMask::ConvertRadiusToSigma(gParams[i].fBlur));
-                paint->setMaskFilter(mf)->unref();
+                paint->setMaskFilter(SkBlurMaskFilter::Make(kNormal_SkBlurStyle,
+                                         SkBlurMask::ConvertRadiusToSigma(gParams[i].fBlur)));
             }
         }
         fLooper = looperBuilder.detach();