RK-A2

We need to start using browser storage. This ticket is to serve as the first use case.

For the purposes of this ticket, a session ends when all tabs and windows of the browser are closed.

Test case:

- Visit a supported page (currently, any youtube page). open the inspect panel.
- Look for total_visits. Let it be X
- Open multiple new tabs. total_visits should still be X.
- Open multiple windows. total_visits should still be X.
- Close all tabs in one window. total_visits should still be X.
- Close all windows and open one window. total_visits is incremented to X+1.
- Close the window and open a window. total_visits is incremented to X+2.