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/SampleApp.cpp b/samplecode/SampleApp.cpp
index 7212223..05d6ce0 100644
--- a/samplecode/SampleApp.cpp
+++ b/samplecode/SampleApp.cpp
@@ -1389,7 +1389,7 @@
     }
 
     if (fSaveToSKP) {
-        SkAutoTUnref<const SkPicture> picture(fRecorder.endRecording());
+        sk_sp<SkPicture> picture(fRecorder.finishRecordingAsPicture());
         SkFILEWStream stream("sample_app.skp");
         picture->serialize(&stream);
         fSaveToSKP = false;
@@ -1398,7 +1398,7 @@
     }
 
     if (fUsePicture) {
-        SkAutoTUnref<const SkPicture> picture(fRecorder.endRecording());
+        sk_sp<SkPicture> picture(fRecorder.finishRecordingAsPicture());
 
         // serialize/deserialize?
         if (false) {
@@ -1406,9 +1406,9 @@
             picture->serialize(&wstream);
 
             SkAutoTDelete<SkStream> rstream(wstream.detachAsStream());
-            picture.reset(SkPicture::CreateFromStream(rstream));
+            picture = SkPicture::MakeFromStream(rstream);
         }
-        orig->drawPicture(picture);
+        orig->drawPicture(picture.get());
     }
 
     // Do this after presentGL and other finishing, rather than in afterChild