add a ClassID function to GrBatch

gm/beziereffects.cpp

Index: gm/beziereffects.cpp
diff --git a/gm/beziereffects.cpp b/gm/beziereffects.cpp
index 1886a4a2b0ae811503045fc42a389dadd4736838..c7ee7c9f529fa2e7b1c77a2e6ec01893fd0e11d1 100644
--- a/gm/beziereffects.cpp
+++ b/gm/beziereffects.cpp
@@ -32,6 +32,7 @@ namespace skiagm {
 
 class BezierCubicOrConicTestBatch : public GrTestBatch {
 public:
+    BATCH_CLASS_ID
     struct Geometry : public GrTestBatch::Geometry {
         SkRect fBounds;
     };
@@ -432,6 +433,7 @@ private:
 
 class BezierQuadTestBatch : public GrTestBatch {
 public:
+    BATCH_CLASS_ID
     struct Geometry : public GrTestBatch::Geometry {
         SkRect fBounds;
     };