Introduce GrBatch subclasses GrDrawBatch and GrVertexBatch to prepare for non-drawing batches

src/gpu/batches/GrBWFillRectBatch.h

Index: src/gpu/batches/GrBWFillRectBatch.h
diff --git a/src/gpu/batches/GrBWFillRectBatch.h b/src/gpu/batches/GrBWFillRectBatch.h
index ff1533caa211b29534b4ca4b4671cb11f5b1a245..c95fd7037bbb25c2a64b6252e4bf288ffcd0196c 100644
--- a/src/gpu/batches/GrBWFillRectBatch.h
+++ b/src/gpu/batches/GrBWFillRectBatch.h
@@ -10,12 +10,12 @@
 
 #include "GrColor.h"
 
-class GrBatch;
+class GrDrawBatch;
 class SkMatrix;
 struct SkRect;
 
 namespace GrBWFillRectBatch {
-GrBatch* Create(GrColor color,
+GrDrawBatch* Create(GrColor color,
                 const SkMatrix& viewMatrix,
                 const SkRect& rect,
                 const SkRect* localRect,