Convert GrBuffer owners to sk_sp

Change-Id: Id49d775c30f01f4de05f385227c5ed5d90d6839e
Reviewed-on: https://skia-review.googlesource.com/c/187920
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
diff --git a/src/gpu/ops/GrAAFillRRectOp.h b/src/gpu/ops/GrAAFillRRectOp.h
index b934fb0..cb29b91 100644
--- a/src/gpu/ops/GrAAFillRRectOp.h
+++ b/src/gpu/ops/GrAAFillRRectOp.h
@@ -66,7 +66,7 @@
     int fInstanceCount = 1;
     int fInstanceStride = 0;
 
-    const GrBuffer* fInstanceBuffer = nullptr;
+    sk_sp<const GrBuffer> fInstanceBuffer;
     int fBaseInstance;
 
     friend class GrOpMemoryPool;