Called by the Router during recognition phase of a navigation.
If this resolves to false, the given navigation is cancelled.
This method delegates to the child component's routerCanDeactivate hook if it exists,
and otherwise resolves to true.
Source
Future<bool> routerCanDeactivate(ComponentInstruction nextInstruction) {
if (_currentInstruction == null) {
return new Future.value(true);
}
return this._componentRef.then((ComponentRef ref) =>
hasLifecycleHook(hook_mod.routerCanDeactivate, ref.instance)
? ((ref.instance as CanDeactivate))
.routerCanDeactivate(nextInstruction, this._currentInstruction)
: true);
}