If Google decides, next week, they will stop releasing any of their own source code (or whatever they borrowed from more-liberal-than-GPL licenses) you can always just fork whatever they already released. You the user - even if you also wrote the original code they based their product on - have no right to demand the release of what they built. They release if they want to.
Free Software is about that: it's about your freedom.
Free Software is about that: it's about your freedom.