Use sk_sp text blob APIs

SkTextBlobBuilder::build()      -> make()
SkAutoTUnref<const SkTextBlob>  -> sk_sp<SkTextBlob>
drawTextBlob(const SkTextBlob*) -> drawTextBlob(const sk_sp<SkTextBlob>&)

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2335493005

Review-Url: https://codereview.chromium.org/2335493005
diff --git a/gm/textblobuseaftergpufree.cpp b/gm/textblobuseaftergpufree.cpp
index c104e9b..44fd854 100644
--- a/gm/textblobuseaftergpufree.cpp
+++ b/gm/textblobuseaftergpufree.cpp
@@ -47,18 +47,18 @@
 
         sk_tool_utils::add_to_text_blob(&builder, text, paint, 10, 10);
 
-        SkAutoTUnref<const SkTextBlob> blob(builder.build());
+        sk_sp<SkTextBlob> blob(builder.make());
 
         // draw textblob
         SkRect rect = SkRect::MakeLTRB(0.f, 0.f, SkIntToScalar(kWidth), kHeight / 2.f);
         SkPaint rectPaint;
         rectPaint.setColor(0xffffffff);
         canvas->drawRect(rect, rectPaint);
-        canvas->drawTextBlob(blob.get(), 10, 50, paint);
+        canvas->drawTextBlob(blob, 10, 50, paint);
 
         // This text should look fine
         canvas->getGrContext()->freeGpuResources();
-        canvas->drawTextBlob(blob.get(), 10, 150, paint);
+        canvas->drawTextBlob(blob, 10, 150, paint);
     }
 
 private: