add missing override

src/gpu/batches/GrStencilPathBatch.h

Index: src/gpu/batches/GrStencilPathBatch.h
diff --git a/src/gpu/batches/GrStencilPathBatch.h b/src/gpu/batches/GrStencilPathBatch.h
index bafcfffc0e3887b31ca4e4e4a16510490ca9814c..d6790091ae90b84a805f7798332b53e862013d79 100644
--- a/src/gpu/batches/GrStencilPathBatch.h
+++ b/src/gpu/batches/GrStencilPathBatch.h
@@ -29,7 +29,7 @@ public:
 
     const char* name() const override { return "StencilPath"; }
 
-    uint32_t renderTargetUniqueID() const { return fRenderTarget.get()->getUniqueID(); }
+    uint32_t renderTargetUniqueID() const override { return fRenderTarget.get()->getUniqueID(); }
 
     SkString dumpInfo() const override {
         SkString string;