[Groxx]

It's a bit of an alarmist, though accurate, alert: anything which has access to your tabs (ie, anything which can observe / inject into a page) also has access to your "history" as it can see what you're browsing. I'm sure other permissions also trip this, but "tabs" is one of the most common, and I ran across it recently too: http://code.google.com/chrome/extensions/tabs.html

edit: I'd assume "history" also trips the history alert: http://code.google.com/chrome/extensions/history.html

edit again: the extension has "tabs" permission only. Very little to worry about, unless you're paranoid about your browsing history.

[chrischen]

If you are paranoid, use incognito. Extensions are disabled in incognito mode by default.