.net core cookies authentication on browser close

I am using cookies authentication in my .net core mvc application. One of the requirements I have is to logout user when the browser is closed. I have set sliding expiration to 5 minutes in app. As expected if the user comes back to the website after 5 minutes user is redirected to login page, but if the user comes back inside 5 minutes the user is logged in automatically. Is there a way to logout user if the browser is closed?

ASP.NET Uploaded File

I have an ASP.NET web application that uses jQuery on client side.
On one of the web forms I have a bunch of controls to fill, and an upload control.
User can run upload while filling other entries on the form.
When user saves the form, all data including file is stored into database .
The question is what to do with uploaded file while user fills the form?
I have two possible solutions, but don’t know which of them is more optimal