I actually have a library that is Mozilla licensed and gets some contributions from the likes of Google, Uber, Airbnb and so on. Mozilla license is similar to GPL in the sense that it also commands you to publish your code in some situations, so I would expect Google to outlaw this license as well, but so far I haven' received any complaints and I don't think the contributors would go out of their way to get permission from higher-ups at Google. Perhaps they didn't notice what terms the Mozilla license implies.