Several sites created for the sole purpose of attempting to force users to install a Chrome extension. These sites are usually redirects from domains that offer cracks, keygens, and adult entertainment sites. When you click anywhere on the website, the audio file, voice.mp3 plays in a continuous loop, which says Click Add to close this page, plays in continuous loop. If your browser is not in full-screen mode, then the code makes it so. Clicking the Add extension button initiates the installation of the app.”]
Source: https://blog.malwarebytes.com/cybercrime/2016/11/forced-into-installing-a-chrome-extension/