SessionController::IsUserSupervised() and IsUserChild() overlap a little bit (a child is supervised, but a "supervised user" may not be a child).

Also, there is lots of code in ash that checks ash::LoginStatus to check the user type, but LoginStatus only partially overlaps session type and user type.

Add a GetActiveUserType() method that returns user_manager::UserType. Replace IsUserChild() calls with it. The method will have to return something when there is no active user, which would mean adding UserType::UNKNOWN = -1 (since there are histograms on UserType) and updating the mojo serializers.

This would be a good intro to the session management code in ash.