Make GrVertexBatch objects hold their own draws during GrDrawTarget flush

src/gpu/batches/GrStrokeRectBatch.h

Index: src/gpu/batches/GrStrokeRectBatch.h
diff --git a/src/gpu/batches/GrStrokeRectBatch.h b/src/gpu/batches/GrStrokeRectBatch.h
index 31b11d9c320d7f55c1c58db960237bdf55c9e583..2e81cc237fa98e495387fbb8ec299a140d738f72 100644
--- a/src/gpu/batches/GrStrokeRectBatch.h
+++ b/src/gpu/batches/GrStrokeRectBatch.h
@@ -38,9 +38,9 @@ public:
 
     void initBatchTracker(const GrPipelineOptimizations&) override;
 
-    void generateGeometry(GrBatchTarget* batchTarget) override;
-
 private:
+    void onPrepareDraws(Target*) override;
+
     GrStrokeRectBatch(const Geometry& geometry, bool snapToPixelCenters);
 
     GrColor color() const { return fBatch.fColor; }