Page Timer is a nice tool from Google which allow us to track the time we spend on a website or tab.
All the data that Page Timer counts is stored in ram and doesn’t store anywhere else. So if you close the tab, you will loose the time.
You can download the extension here: https://chrome.google.com/webstore/detail/page-timer/enljfpkeopdppbphgadibdpodgjhmabm
Enjoy smile