Consolidate GPU buffer implementations

src/gpu/batches/GrTInstanceBatch.h

Index: src/gpu/batches/GrTInstanceBatch.h
diff --git a/src/gpu/batches/GrTInstanceBatch.h b/src/gpu/batches/GrTInstanceBatch.h
index 22d4f527920feb9d62a879f2d51e3d9a0f84a384..fdd0662d069fd432e5852533a486c2d460444868 100644
--- a/src/gpu/batches/GrTInstanceBatch.h
+++ b/src/gpu/batches/GrTInstanceBatch.h
@@ -34,7 +34,7 @@
  *     const GrGeometryProcessor* CreateGP(const Geometry& seedGeometry,
  *                                         const GrXPOverridesForBatch& overrides)
  *
- *     const GrIndexBuffer* GetIndexBuffer(GrResourceProvider*)
+ *     const GrBuffer* GetIndexBuffer(GrResourceProvider*)
  *
  *     Tesselate(intptr_t vertices, size_t vertexStride, const Geometry& geo,
  *               const GrXPOverridesForBatch& overrides)
@@ -101,7 +101,7 @@ private:
         size_t vertexStride = gp->getVertexStride();
         int instanceCount = fGeoData.count();
 
-        SkAutoTUnref<const GrIndexBuffer> indexBuffer(
+        SkAutoTUnref<const GrBuffer> indexBuffer(
                 Impl::GetIndexBuffer(target->resourceProvider()));
         InstancedHelper helper;
         void* vertices = helper.init(target, kTriangles_GrPrimitiveType, vertexStride,