create and thread batch tracker object

src/gpu/GrOptDrawState.h

Index: src/gpu/GrOptDrawState.h
diff --git a/src/gpu/GrOptDrawState.h b/src/gpu/GrOptDrawState.h
index 542172fd642e032135ea6502de24e08d7f755790..1d8be1b2c2f877cc1d1d2f1b700171d4dbec6320 100644
--- a/src/gpu/GrOptDrawState.h
+++ b/src/gpu/GrOptDrawState.h
@@ -84,6 +84,7 @@ public:
 
     bool hasGeometryProcessor() const { return SkToBool(fGeometryProcessor.get()); }
     const GrGeometryProcessor* getGeometryProcessor() const { return fGeometryProcessor.get(); }
+    const GrBatchTracker& getBatchTracker() const { return fBatchTracker; }
     const GrPendingFragmentStage& getColorStage(int idx) const {
         SkASSERT(idx < this->numColorStages());
         return fFragmentStages[idx];
@@ -243,6 +244,7 @@ private:
     GrBlendCoeff                        fDstBlend;
     uint32_t                            fFlags;
     ProgramGeometryProcessor            fGeometryProcessor;
+    GrBatchTracker                      fBatchTracker;
     FragmentStageArray                  fFragmentStages;
 
     // This function is equivalent to the offset into fFragmentStages where coverage stages begin.