Looks like just one, from the list of major contributors. But, Google really has no right to whine about this. They make an explicit tradeoff: they manage to s

Looks like just one, from the list of major contributors. But, Google really has no right to whine about this. They make an explicit tradeoff: they manage to stay 3-5 years ahead of the curve of everyone else by not open sourcing their impressive libraries and infrastructure. But the corollary of that is that there's no place to whine "we got there first!" when someone else produces an implementation of X.