iaus-update-listener.kt

// Create a listener to track downloading state updates.
val listener = InstallStateUpdatedListener { state -> 
    // Update progress indicator, request user to approve app reload, etc.
}

// At some point before starting an update, register a listener for updates.
appUpdateManager.registerListener(listener)

// ...

// At some point when status updates are no longer needed, unregister the listener.
appUpdateManager.unregisterListener(listener)