update textblob api to use sk_sp

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2236013002

NOTREECHECKS=True

Review-Url: https://codereview.chromium.org/2236013002
diff --git a/include/core/SkTextBlob.h b/include/core/SkTextBlob.h
index 3c5d873..1addb6f 100644
--- a/include/core/SkTextBlob.h
+++ b/include/core/SkTextBlob.h
@@ -43,7 +43,11 @@
      *  @return A new SkTextBlob representing the serialized data, or NULL if the buffer is
      *          invalid.
      */
-    static const SkTextBlob* CreateFromBuffer(SkReadBuffer&);
+    static sk_sp<SkTextBlob> MakeFromBuffer(SkReadBuffer&);
+
+    static const SkTextBlob* CreateFromBuffer(SkReadBuffer& buffer) {
+        return MakeFromBuffer(buffer).release();
+    }
 
     enum GlyphPositioning {
         kDefault_Positioning      = 0, // Default glyph advances -- zero scalars per glyph.
@@ -99,7 +103,11 @@
      *  Returns an immutable SkTextBlob for the current runs/glyphs. The builder is reset and
      *  can be reused.
      */
-    const SkTextBlob* build();
+    sk_sp<SkTextBlob> make();
+
+    const SkTextBlob* build() {
+        return this->make().release();
+    }
 
     /**
      *  Glyph and position buffers associated with a run.