It's quite easy. You initialize the timer based on millisecond times for the start/end time. That way it survives refreshes.
E.g. 'start timer' logs the unix ms time it starts to db/cookies and duration / direction (count up/down) Then all you need to do is initialize the timer correctly on...
@Jaxel They want to be able to do OCR (Optical Character Recognition) to fill fields / data automatically.
For PubG There is probably even an API they can use.