Another geek portmanteau - malware and advertising: malvertising...
While bogus tech support / FBI warning pop-ups and pornados have been pretty much countered by browser security features, this method is a work around that would give most normal users consternation and worry.
For now, it appears to be Windows Chrome specific and odds are Google will deal with it quickly.
See this article from Malwarebytes (who discovered the malware) on how to deal with it. Just another reason to use an ad blocker and to never EVER click on any ads you see while browsing the web.
The Malwarebytes product has been around for years and is an excellent product. While I do not use it as my primary antivirus/PC security product, I do have it on a USB drive that I use to periodically check my system and clean-up friends computers that have problems.