Nobody cares what stupid things you do, i would never convert mp3 to ogg as there is no logic behind it. Maybe from ogg to mp3 for simple mobile players...
I think its only available on Google device, like the Chromebooks. Also, I dont think you can get it on your pc...yet. Who knows, maybe I havent searched enough.
According to Google’s tests, WebP can result in around a ~39 percent reduction in file-size compared to the image formats commonly used for the web today.