Add a startup test that delays runApp (#91346)

diff --git a/TESTOWNERS b/TESTOWNERS
index 7155b7f..7ce44b7 100644
--- a/TESTOWNERS
+++ b/TESTOWNERS
@@ -34,6 +34,7 @@
 /dev/devicelab/bin/tasks/flutter_gallery__image_cache_memory.dart @zanderso @flutter/engine
 /dev/devicelab/bin/tasks/flutter_gallery__memory_nav.dart @zanderso @flutter/engine
 /dev/devicelab/bin/tasks/flutter_gallery__start_up.dart @zanderso @flutter/engine
+/dev/devicelab/bin/tasks/flutter_gallery__start_up_delayed.dart @dnfield @flutter/engine
 /dev/devicelab/bin/tasks/flutter_gallery__transition_perf_e2e.dart @zanderso @flutter/engine
 /dev/devicelab/bin/tasks/flutter_gallery__transition_perf_hybrid.dart @zanderso @flutter/engine
 /dev/devicelab/bin/tasks/flutter_gallery__transition_perf_with_semantics.dart @zanderso @flutter/engine