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

tests/GrPorterDuffTest.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkXfermode.h"
 #include "Test.h"
 
@@ skipping 880 matching lines @@
                 TEST_ASSERT(xpi.fBlendInfo.fWriteColor);
                 break;
             default:
                 ERRORF(reporter, "Invalid xfermode.");
                 break;
         }
     }
 }
 
 static void test_lcd_coverage(skiatest::Reporter* reporter, const GrCaps& caps) {
-    class : public GrBatch {
+    class : public GrVertexBatch {
         void getInvariantOutputColor(GrInitInvariantOutput* out) const override {
             out->setKnownFourComponents(GrColorPackRGBA(123, 45, 67, 221));
         }
 
         void getInvariantOutputCoverage(GrInitInvariantOutput* out) const override {
             out->setUnknownFourComponents();
             out->setUsingLCDCoverage();
         }
 
         const char* name() const override { return "Test LCD Text Batch"; }
@@ skipping 96 matching lines @@
                 TEST_ASSERT(!xp->hasSecondaryOutput());
                 xp->getOptimizations(colorPOI, covPOI, false, 0, caps);
                 TEST_ASSERT(!xp->hasSecondaryOutput());
             }
         }
     }
 }
 
 #endif