Message from Norton or scam?

I keep getting a message from Google Chrome/Norton 360 which says:  "The computer [number] is attempting to access Google Chrome on your computer.  Do you want to allow his connection?"  Then I have to make a choice - but how do I know what computer that is?  Where do I find the numbers?  Is it my laptop? Is it someone else trying to hack in?  I am afraid to select anything