It's probably requesting "tabs" permissions. The Chrome security permissions aren't fine grained enough so often you need to request permission for a lot more than you actually need. For some reason requesting "tabs" shows a scary warning about having access to all your history. You'll find that a ton of extensions need access to your history for this reason, it's actually really annoying as an extension developer.
That's the priveledge that Chrome extensions require in order to inspect URLs as you load them, so they can conditionally apply themselves to the appropriate site(s). As far as I know, there isn't a more granular priveledge to allow access only to URLs as they're loaded (which an extension could still use to track your browsing habits by storing them in its localStorage).
If you type into Chrome's URL/browser bar, it sends the query to google's servers which in turn returns a list of possible search suggestions (autocomplete style). Google likely retains the query for commercialisation purposes.
So the user being worried about a Chrome plugin sending browsing data seems bizarre.
So, when I click a link on HN, using Chrome, Chrome is sending that information to Google? Likewise when I type http://somethingorother, that's going through Google first?