Remove batchtracker

src/gpu/batches/GrVertexBatch.h

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef GrVertexBatch_DEFINED
 #define GrVertexBatch_DEFINED
 
@@ skipping 61 matching lines @@
     // the batch's GrPipeline.
     struct DrawArray {
         SkSTArray<1, GrVertices, true>                      fDraws;
         GrPendingProgramElement<const GrPrimitiveProcessor> fPrimitiveProcessor;
     };
 
     // Array of DrawArray. There may be inline uploads between each DrawArray and each DrawArray
     // may use a different primitive processor.
     SkTLList<DrawArray> fDrawArrays;
 
-    // What is this?
-    GrBatchTracker      fBatchTracker;
-
     typedef GrDrawBatch INHERITED;
 };
 
 #endif