ArsTechnica describes how adware vendors are buying Chrome add-ons so that they can inject malware and ads... And here an account of a developer who sold his Chrome add-on.

It got to the point where the "safe" browser is no longer safer. It just shows that the problems was not really Internet Explorer, which lately with Enhanced Protected Mode, SmartScreening and other features is a lot safer than people remember.

Did you change browser because of "security"?