Revert of Consolidate GPU buffer implementations

src/gpu/batches/GrNonAAFillRectBatch.cpp

Index: src/gpu/batches/GrNonAAFillRectBatch.cpp
diff --git a/src/gpu/batches/GrNonAAFillRectBatch.cpp b/src/gpu/batches/GrNonAAFillRectBatch.cpp
index 5e9d1769b510022d7a73145085eba74100402761..09643444d08314df981df6fc6fd1fa6ea53bf52f 100644
--- a/src/gpu/batches/GrNonAAFillRectBatch.cpp
+++ b/src/gpu/batches/GrNonAAFillRectBatch.cpp
@@ -26,7 +26,7 @@
         out->setKnownSingleComponent(0xff);
     }
 
-    static const GrBuffer* GetIndexBuffer(GrResourceProvider* rp) {
+    static const GrIndexBuffer* GetIndexBuffer(GrResourceProvider* rp) {
         return rp->refQuadIndexBuffer();
     }