1. override
void didReplace(Route oldRoute)

Called after install() when the route replaced another in the navigator.

Source 

@override
void didReplace(Route<dynamic> oldRoute) {
  if (oldRoute is TransitionRoute<dynamic>)
    _controller.value = oldRoute._controller.value;
  _animation.addStatusListener(_handleStatusChanged);
  super.didReplace(oldRoute);
}