Closing Chrome browser does not fire pagehide

When a user closes chrome while logged in to my system, I want to save some stats in our db as if they had properly used the sign out link. I have it working when the user navigates away, or when the user closes ONE the tab of multiple open tabs but not when the user closes the entire browser. What am I missing?

I added a onpagehide event handler that uses navigator.sendBeacon to update my db.

When the user navigates away, or when the user closes ONE the tab of multiple open tabs, the event handler fires and updates the db.

But when the user closes the entire browser, the event does not fire so the db is not updated.

window.addEventListener('pagehide', function() {ProcessLogout();});