Use sk_sp text blob APIs

gm/textblobrandomfont.cpp

Index: gm/textblobrandomfont.cpp
diff --git a/gm/textblobrandomfont.cpp b/gm/textblobrandomfont.cpp
index 583f4fc5b346233f3961d404478858fa35e0b407..a2e46972b417a6629f6628dad7f0e2245abdcdc4 100644
--- a/gm/textblobrandomfont.cpp
+++ b/gm/textblobrandomfont.cpp
@@ -77,7 +77,7 @@ protected:
         }
 
         // build
-        fBlob.reset(builder.build());
+        fBlob = builder.make();
     }
 
     SkString onShortName() override {
@@ -136,7 +136,7 @@ protected:
     }
 
 private:
-    SkAutoTUnref<const SkTextBlob> fBlob;
+    sk_sp<SkTextBlob> fBlob;
 
     static constexpr int kWidth = 2000;
     static constexpr int kHeight = 1600;