Chrome pop up on android

[Ghostsong]

My wife's phone keeps popping up with a pop up saying she's won a free iPhone with a faked Facebook page underneath it. It happened last week on WiFi so I cleared her cache and it went away. Now today it's back over 4g. I cleared the cache and disabled the JavaScript on it. AVG isn't picking anything up. Her phone isn't rooted and she hasn't downloaded any new apps in the past year. Thoughts? Could it be an ad on some site she's visiting?

 

[carnageX]

I would say most likely an ad on a site she's visiting. Check what sites she's going to and see if any are sketchy or pop it up when visiting them.