Iterate over instanced draws in GrGpu rather than above GrBatchTarget

Review URL: https://codereview.chromium.org/1127273007
diff --git a/src/gpu/GrTest.cpp b/src/gpu/GrTest.cpp
index 727fbbc..1017273 100644
--- a/src/gpu/GrTest.cpp
+++ b/src/gpu/GrTest.cpp
@@ -199,7 +199,7 @@
 
     void onClearStencilClip(GrRenderTarget*, const SkIRect& rect, bool insideClip) override {}
 
-    void onDraw(const DrawArgs&, const GrVertices&) override {}
+    void onDraw(const DrawArgs&, const GrNonInstancedVertices&) override {}
 
     void onStencilPath(const GrPath* path, const StencilPathState& state) override {}