Update SkAlphaThresholdFilter to sk_sp

tests/FlattenableFactoryToName.cpp

Index: tests/FlattenableFactoryToName.cpp
diff --git a/tests/FlattenableFactoryToName.cpp b/tests/FlattenableFactoryToName.cpp
index 28d491b26fdf1f0a8babae4491e5b74e6e298c56..a22f0b1c3e79d04f0ea09724d507ac0d3de2f86f 100644
--- a/tests/FlattenableFactoryToName.cpp
+++ b/tests/FlattenableFactoryToName.cpp
@@ -29,8 +29,8 @@ DEF_TEST(FlattenableFactoryToName, r) {
     rects[1] = SkIRect::MakeXYWH(150, 0, 200, 500);
     SkRegion region;
     region.setRects(rects, 2);
-    SkAutoTUnref<SkImageFilter> filter( SkAlphaThresholdFilter::Create(region, 0.2f, 0.7f));
-    test_flattenable(r, filter, "SkAlphaThresholdFilter()");
+    sk_sp<SkImageFilter> filter(SkAlphaThresholdFilter::Make(region, 0.2f, 0.7f, nullptr));
+    test_flattenable(r, filter.get(), "SkAlphaThresholdFilter()");
 
     SkBitmap bm;
     bm.allocN32Pixels(8, 8);