Replace timeout/scaling macros with functions.
diff --git a/test/core/end2end/tests/write_buffering.c b/test/core/end2end/tests/write_buffering.c
index 50c0ed7..abf90ca 100644
--- a/test/core/end2end/tests/write_buffering.c
+++ b/test/core/end2end/tests/write_buffering.c
@@ -58,7 +58,7 @@
 }
 
 static gpr_timespec n_seconds_time(int n) {
-  return GRPC_TIMEOUT_SECONDS_TO_DEADLINE(n);
+  return grpc_timeout_seconds_to_deadline(n);
 }
 
 static gpr_timespec five_seconds_time(void) { return n_seconds_time(5); }
@@ -74,7 +74,7 @@
   if (!f->server) return;
   grpc_server_shutdown_and_notify(f->server, f->cq, tag(1000));
   GPR_ASSERT(grpc_completion_queue_pluck(
-                 f->cq, tag(1000), GRPC_TIMEOUT_SECONDS_TO_DEADLINE(5), NULL)
+                 f->cq, tag(1000), grpc_timeout_seconds_to_deadline(5), NULL)
                  .type == GRPC_OP_COMPLETE);
   grpc_server_destroy(f->server);
   f->server = NULL;