return pictures as sk_sp

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1811703002

Review URL: https://codereview.chromium.org/1811703002
diff --git a/samplecode/SampleTiling.cpp b/samplecode/SampleTiling.cpp
index 125155e..62f055f 100644
--- a/samplecode/SampleTiling.cpp
+++ b/samplecode/SampleTiling.cpp
@@ -54,7 +54,7 @@
 static const int gHeight = 32;
 
 class TilingView : public SampleView {
-    SkAutoTUnref<SkPicture>     fTextPicture;
+    sk_sp<SkPicture>     fTextPicture;
     SkAutoTUnref<SkDrawLooper>  fLooper;
 public:
     TilingView()
@@ -153,11 +153,11 @@
 
         if (textCanvas) {
             SkASSERT(nullptr == fTextPicture);
-            fTextPicture.reset(recorder.endRecording());
+            fTextPicture = recorder.finishRecordingAsPicture();
         }
 
         SkASSERT(fTextPicture);
-        canvas->drawPicture(fTextPicture);
+        canvas->drawPicture(fTextPicture.get());
     }
 
 private: