Bring sk_sp to GrDrawContext

gm/rrects.cpp

Index: gm/rrects.cpp
diff --git a/gm/rrects.cpp b/gm/rrects.cpp
index d8b5e388eb953fea2fdc739d1793346f5a730c7c..57c11ada5626f7d6912f898b4fcfb5f8f21c63a2 100644
--- a/gm/rrects.cpp
+++ b/gm/rrects.cpp
@@ -66,14 +66,14 @@ protected:
 #if SK_SUPPORT_GPU
         GrRenderTarget* rt = canvas->internal_private_accessTopLayerRenderTarget();
         context = rt ? rt->getContext() : nullptr;
-        SkAutoTUnref<GrDrawContext> drawContext;
+        sk_sp<GrDrawContext> drawContext;
         if (kEffect_Type == fType) {
             if (!context) {
                 skiagm::GM::DrawGpuOnlyMessage(canvas);
                 return;
             }
 
-            drawContext.reset(context->drawContext(rt));
+            drawContext = context->drawContext(sk_ref_sp(rt));
             if (!drawContext) {
                 return;
             }