Make sp variants for SkData

Review URL: https://codereview.chromium.org/1779263003
diff --git a/src/images/SkImageDecoder_ktx.cpp b/src/images/SkImageDecoder_ktx.cpp
index 539795a..1566745 100644
--- a/src/images/SkImageDecoder_ktx.cpp
+++ b/src/images/SkImageDecoder_ktx.cpp
@@ -50,12 +50,12 @@
 
 SkImageDecoder::Result SkKTXImageDecoder::onDecode(SkStream* stream, SkBitmap* bm, Mode mode) {
     // TODO: Implement SkStream::copyToData() that's cheap for memory and file streams
-    SkAutoDataUnref data(SkCopyStreamToData(stream));
+    auto data = SkCopyStreamToData(stream);
     if (nullptr == data) {
         return kFailure;
     }
 
-    SkKTXFile ktxFile(data);
+    SkKTXFile ktxFile(data.get());
     if (!ktxFile.valid()) {
         return kFailure;
     }