From email with gab@:

"Lucky Luke is enabled on Android today indeed. IMO a change to tell the TaskScheduler to go through "shutdown" when going into background would make sense on Android.

We just need to have an equivalent of task_scheduler::internals::TaskTracker::Shutdown() which isn't a one time thing ,e.g. task_scheduler::internals::TaskTracker::FlushShutdownTasks() and call it synchronously when ChromeAndroid receives the backgrounded signal :). This sounds like a great opportunity to have some sort of "clean shutdown" phase on Android!"