Unless you actually have McAfee installed (which I wouldn't recommend, since it's a resource hog and doesn't really make you much safer), then this popup is most likely a bogus scam popup related to the website you were visiting. Avoid that website.
I may have shared these before, but it's always worth another look to refresh your memory:
Smartphones have brought out various kinds of neurotic and paranoid reactions from users. The technology is difficult to understand, and it is easy for us to allow ourselves to suspect that bad things are happening, when in fact they’re not. Android Central regularly receives posts from guests...
forums.androidcentral.com
Let's face it, malware is a fact of life. As long as there are personal mobile devices, there will be worthless shambling piles of meat that will try their best to exploit them for unscrupulous financial gain or worse. But contrary to what all of those urgent and breathless articles about the...
forums.androidcentral.com