Convert SkAutoTUnref<SkData> to sk_sp<SkData>.

With the move from SkData::NewXXX to SkData::MakeXXX most
SkAutoTUnref<SkData> were changed to sk_sp<SkData>. However,
there are still a few SkAutoTUnref<SkData> around, so clean
them up.

Review-Url: https://codereview.chromium.org/2212493002
diff --git a/samplecode/SampleFilterFuzz.cpp b/samplecode/SampleFilterFuzz.cpp
index 7a53f4f..755e8fb 100644
--- a/samplecode/SampleFilterFuzz.cpp
+++ b/samplecode/SampleFilterFuzz.cpp
@@ -738,7 +738,7 @@
 
 static SkImageFilter* make_serialized_image_filter() {
     sk_sp<SkImageFilter> filter(make_image_filter(false));
-    SkAutoTUnref<SkData> data(SkValidatingSerializeFlattenable(filter.get()));
+    sk_sp<SkData> data(SkValidatingSerializeFlattenable(filter.get()));
     const unsigned char* ptr = static_cast<const unsigned char*>(data->data());
     size_t len = data->size();
 #ifdef SK_ADD_RANDOM_BIT_FLIPS