Fix filter_latency test for sockpair and fd fixtures.
diff --git a/test/core/end2end/tests/filter_latency.c b/test/core/end2end/tests/filter_latency.c
index 8bcb313..2c9a052 100644
--- a/test/core/end2end/tests/filter_latency.c
+++ b/test/core/end2end/tests/filter_latency.c
@@ -325,6 +325,9 @@
   grpc_channel_init_register_stage(GRPC_CLIENT_CHANNEL, INT_MAX,
                                    maybe_add_filter,
                                    (void *)&test_client_filter);
+  grpc_channel_init_register_stage(GRPC_CLIENT_DIRECT_CHANNEL, INT_MAX,
+                                   maybe_add_filter,
+                                   (void *)&test_client_filter);
   grpc_channel_init_register_stage(GRPC_SERVER_CHANNEL, INT_MAX,
                                    maybe_add_filter,
                                    (void *)&test_server_filter);