Fix memory leak

TBR=bsalomon@google.com
BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1706773002

Review URL: https://codereview.chromium.org/1706773002
diff --git a/src/gpu/GrPathRenderingDrawContext.h b/src/gpu/GrPathRenderingDrawContext.h
index ab36955..49a0e1d 100644
--- a/src/gpu/GrPathRenderingDrawContext.h
+++ b/src/gpu/GrPathRenderingDrawContext.h
@@ -29,11 +29,10 @@
     GrPathRenderingDrawContext(GrContext* ctx, GrDrawingManager* mgr, GrRenderTarget* rt,
                                const SkSurfaceProps* surfaceProps, GrAuditTrail* at,
                                GrSingleOwner* so)
-        : INHERITED(ctx, mgr, rt, surfaceProps, at, so)
-        , fStencilAndCoverTextContext(nullptr) {}
+        : INHERITED(ctx, mgr, rt, surfaceProps, at, so) {}
 
 private:
-    GrStencilAndCoverTextContext* fStencilAndCoverTextContext;
+    SkAutoTDelete<GrStencilAndCoverTextContext> fStencilAndCoverTextContext;
 
     friend class GrDrawingManager; // for ctor