change flattenable factory to return sk_sp

src/effects/SkMagnifierImageFilter.cpp

Index: src/effects/SkMagnifierImageFilter.cpp
diff --git a/src/effects/SkMagnifierImageFilter.cpp b/src/effects/SkMagnifierImageFilter.cpp
index bfad5494853d0011d765d8bbf1fb351028d7b604..dfd7f04f6a88231eebf3a5644f009980e9948e72 100644
--- a/src/effects/SkMagnifierImageFilter.cpp
+++ b/src/effects/SkMagnifierImageFilter.cpp
@@ -281,11 +281,11 @@ bool SkMagnifierImageFilter::asFragmentProcessor(GrFragmentProcessor** fp,
 }
 #endif
 
-SkFlattenable* SkMagnifierImageFilter::CreateProc(SkReadBuffer& buffer) {
+sk_sp<SkFlattenable> SkMagnifierImageFilter::CreateProc(SkReadBuffer& buffer) {
     SK_IMAGEFILTER_UNFLATTEN_COMMON(common, 1);
     SkRect src;
     buffer.readRect(&src);
-    return Create(src, buffer.readScalar(), common.getInput(0).get());
+    return sk_sp<SkFlattenable>(Create(src, buffer.readScalar(), common.getInput(0).get()));
 }
 
 void SkMagnifierImageFilter::flatten(SkWriteBuffer& buffer) const {