popRoute method
Called by the Router when the Router.backButtonDispatcher reports that the operating system is requesting that the current route be popped.
The method should return a boolean Future to indicate whether this delegate handles the request. Returning false will cause the entire app to be popped.
Consider using a SynchronousFuture if the result can be computed synchronously, so that the Router does not need to wait for the next microtask to schedule a build.
Implementation
@override
Future<bool> popRoute() async => controller.maybePopTop();