Add a base class for GrIODB that handles geometry data

src/gpu/GrDrawTarget.h

Index: src/gpu/GrDrawTarget.h
diff --git a/src/gpu/GrDrawTarget.h b/src/gpu/GrDrawTarget.h
index 76953655037b82ee033e5238dcc9f005d2627c64..c7f45d32cae834cef6dd29019a57dc3c0b1d3dd5 100644
--- a/src/gpu/GrDrawTarget.h
+++ b/src/gpu/GrDrawTarget.h
@@ -579,7 +579,10 @@ public:
         GrPendingIOResource<const GrIndexBuffer, kRead_GrIOType>  fIndexBuffer;
     };
 
-    virtual void setDrawBuffers(DrawInfo*) = 0;;
+    /**
+     * Used to populate the vertex and index buffer on the draw info before onDraw is called.
+     */
+    virtual void setDrawBuffers(DrawInfo*, size_t vertexStride) = 0;;
     bool programUnitTest(int maxStages);
 
 protected: