It's a Trap!
I'm Admiral Ackbar and I'm here to show you how much careful you must be with Chrome Extensions permissions. This extension can access the content of pages you visit and I think this is pretty huge. Don't you? Wait for 20 seconds and don't do anything on this computer. It will indicate to the extension that you're away and not looking at the screen. Then you'll start to see some things happening while you're not suppossed to pay attention at your screen.