History controller is in charge of allowing navigating back and forward in the search interface history.
Move backward in the interface history.
Promise<void>: A promise that resolves when the previous state has been restored.
Move forward in the interface history.
Promise<void>: A promise that resolves when the next state has been restored.
Adds a callback that will be called on state change.
() ⇒ void
A callback to be invoked on state change.
Unsubscribe: An unsubscribe function to remove the listener.
The state relevant to the
History controller instance.
The headless engine.