Refactor progress
diff --git a/src/core/transport/transport.h b/src/core/transport/transport.h
index 7f60fdc..9d43581 100644
--- a/src/core/transport/transport.h
+++ b/src/core/transport/transport.h
@@ -64,18 +64,15 @@
 
 /* Transport op: a set of operations to perform on a transport */
 typedef struct grpc_transport_op {
-  void (*on_consumed)(void *user_data, int success);
-  void *on_consumed_user_data;
+  grpc_iomgr_closure *on_consumed;
 
   grpc_stream_op_buffer *send_ops;
   int is_last_send;
-  void (*on_done_send)(void *user_data, int success);
-  void *send_user_data;
+  grpc_iomgr_closure *on_done_send;
 
   grpc_stream_op_buffer *recv_ops;
   grpc_stream_state *recv_state;
-  void (*on_done_recv)(void *user_data, int success);
-  void *recv_user_data;
+  grpc_iomgr_closure *on_done_recv;
 
   grpc_pollset *bind_pollset;