Also from Chrome Web Store,but first you need to install this Opera extension :

https://addons.opera.com/en/extensions/details/download-chrome-extension-9/?display=en

I am not sure if AOS addon is going to work in Opera.Try it and tell us if it works in Opera.

Edit:
AOS is available at Opera Extensions also :

https://addons.opera.com/en/extensions/details/avast-online-security/?display=en