Make sp variants for SkData

src/images/SkImageDecoder_astc.cpp

Index: src/images/SkImageDecoder_astc.cpp
diff --git a/src/images/SkImageDecoder_astc.cpp b/src/images/SkImageDecoder_astc.cpp
index 8989464f3b8d0ee4d25989de165f5c60b5b0963f..30d65f1f0f32b3899d0f065a3e63acce37980bb2 100644
--- a/src/images/SkImageDecoder_astc.cpp
+++ b/src/images/SkImageDecoder_astc.cpp
@@ -44,7 +44,7 @@ static inline int read_24bit(const uint8_t* buf) {
 }
 
 SkImageDecoder::Result SkASTCImageDecoder::onDecode(SkStream* stream, SkBitmap* bm, Mode mode) {
-    SkAutoTUnref<SkData> data(SkCopyStreamToData(stream));
+    auto data = SkCopyStreamToData(stream);
     if (!data || !data->size()) {
         return kFailure;
     }