Yet another reason I'm glad I don't use Chrome. As for the ad network, I would not be surprised if there's a lot more information being gleaned from it, but it makes sense they would want to tie it back to search if possible.
I just assume everything, hence why I don't use it. Paranoid much? Maybe, but it doesn't mean I'm wrong ;-) Knowing the ethos of Google, I don't trust it any further than I can throw it.
- "Clickstream" data from Chrome. Sorry I don't have the source in hand, but I remember that Rand Fishkin was talking about it some time ago.
- Statistical analysis on the SERP (eg. if you search for something, click a link, go back and pick another result, that is a bounce)
- This is just speculation, but I'd say their ad network can be a source too