Why is this person being so vehemently downvoted? Anyone who has ever tried browsing the web for more than a couple minutes on a computer without an ad-blocker has run into fake download button ads. As they point out in a later comment, getpaint.net has them: I literally just went on there right now and what do you know: http://i.imgur.com/Ygjyn3H.png . If I go to Sourceforge, another malicious Google ad for "antivirus" software that at best just scams people out of their money then does nothing: http://imgur.com/a/WlcQB .
Once while visiting my family I happened to be at the dinner table with my parents when my mom mumbled something about a message prompting her to update. Just out of curiosity I walked over and saw her about to click on a completely fake Java update message that would have almost certainly installed malware... served by Google.
It's counterproductive to live in denial of this massive problem. The original commenter has posted evidence; if you want to deny this claim, you ought to be prepared to supply some of your own.