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/bench/CodecBench.h b/bench/CodecBench.h
index b465eae..5b4db24 100644
--- a/bench/CodecBench.h
+++ b/bench/CodecBench.h
@@ -32,7 +32,7 @@
     SkString                fName;
     const SkColorType       fColorType;
     const SkAlphaType       fAlphaType;
-    SkAutoTUnref<SkData>    fData;
+    sk_sp<SkData>           fData;
     SkImageInfo             fInfo;          // Set in onDelayedSetup.
     SkAutoMalloc            fPixelStorage;
     typedef Benchmark INHERITED;