[throwaway91111]

Well, Facebook doesn't have access to your browsing history. At least not most of it, though it's probably still, you know, more that enough to cause a lot of pain.

Google does have access in some situations (chrome + linked profile), but as far as I know they don't sell that access.

Of course, both offer some subset of information for users.

[korethr]

Unless you are using an ad-blocker to block the rather commonplace facebook widget, and their other tracking mechanisms, they may well have more of your browsing history than you realize.

Hell, I do use ad-blockers and block assets coming from known Facebook domains, and they probably still have more information about my browsing history than I realize.