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

src/gpu/GrTargetCommands.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 GrTargetCommands_DEFINED
 #define GrTargetCommands_DEFINED
 
@@ skipping 214 matching lines @@
 
         SkIPoint    fDstPoint;
         SkIRect     fSrcRect;
 
     private:
         GrPendingIOResource<GrSurface, kWrite_GrIOType> fDst;
         GrPendingIOResource<GrSurface, kRead_GrIOType> fSrc;
     };
 
     struct DrawBatch : public Cmd {
-        DrawBatch(GrBatch* batch, GrBatchTarget* batchTarget)
+        DrawBatch(GrDrawBatch* batch, GrBatchTarget* batchTarget)
             : Cmd(kDrawBatch_CmdType)
             , fBatch(SkRef(batch))
             , fBatchTarget(batchTarget) {
             SkASSERT(!batch->isUsed());
         }
 
-        GrBatch* batch() { return fBatch; }
+        GrDrawBatch* batch() { return fBatch; }
         void execute(GrGpu*) override;
 
     private:
-        SkAutoTUnref<GrBatch>  fBatch;
-        GrBatchTarget*         fBatchTarget;
+        SkAutoTUnref<GrDrawBatch>   fBatch;
+        GrBatchTarget*              fBatchTarget;
     };
 
     static const int kCmdBufferInitialSizeInBytes = 8 * 1024;
 
     typedef void* TCmdAlign; // This wouldn't be enough align if a command used long double.
     typedef GrTRecorder<Cmd, TCmdAlign> CmdBuffer;
 
     CmdBuffer* cmdBuffer() { return &fCmdBuffer; }
     GrBatchTarget* batchTarget() { return &fBatchTarget; }
 
     CmdBuffer                           fCmdBuffer;
     GrBatchTarget                       fBatchTarget;
 };
 
 #endif