Reland of add a ClassID function to GrBatch

src/gpu/batches/GrTInstanceBatch.h

Index: src/gpu/batches/GrTInstanceBatch.h
diff --git a/src/gpu/batches/GrTInstanceBatch.h b/src/gpu/batches/GrTInstanceBatch.h
index e314959bfcd9c7d4ff0745ff336c2302f219f389..014ec125fe6ae894d2a1317839046298b79615bb 100644
--- a/src/gpu/batches/GrTInstanceBatch.h
+++ b/src/gpu/batches/GrTInstanceBatch.h
@@ -40,6 +40,8 @@
 template <typename Impl>
 class GrTInstanceBatch : public GrVertexBatch {
 public:
+    DEFINE_BATCH_CLASS_ID
+
     typedef typename Impl::Geometry Geometry;
 
     static GrTInstanceBatch* Create() { return new GrTInstanceBatch; }
@@ -72,9 +74,7 @@
     }
 
 private:
-    GrTInstanceBatch() {
-        this->initClassID<GrTInstanceBatch<Impl>>();
-
+    GrTInstanceBatch() : INHERITED(ClassID()) {
         // Push back an initial geometry
         fGeoData.push_back();
     }
@@ -136,6 +136,8 @@
 
     GrPipelineOptimizations fOpts;
     SkSTArray<1, Geometry, true> fGeoData;
+
+    typedef GrVertexBatch INHERITED;
 };
 
 #endif