Google's got something ahead of the antivirus vendors... they're paying to prevent the hole from being open rather than setting up to block what comes in the hole. Chrome's main problem has been "feature not implemented" rather than takeovers that were seen in the early days of Internet Explorer. ChromeOS products are looking to be cheap user machines, and there's yet to be a need for antivirus there.
Factor the price of an antivirus subscription into every Windows machine you're running, and maybe non-programming businesses could switch to Google products in place of Windows.