Quite a lot, and it’s not just Norton. Google does the same, and pays companies to secretly include Chrome in their installers and auto-updaters, like they included the Google Toolbars before.

Here’s an interview with the VLC developers, where the VLC developers complain how Google tried to get them to secretly install Chrome with it, and offered enormous amounts of money, but they obviously said no: https://www.youtube.com/watch?v=jWx1P93nS0c&t=48s