See the first comment in which I detail my experience with Google ATAP which mirrors the OP's story. She demoed her invention in an interview with them & they patented it without her knowledge/consent.
I've spoken with some of these people and hear there are many more examples yet those people put it behind them or don't want to come out against the biggest tech company. That's too bad as for too long in history those in power and position have stolen from the rightful creators.
https://news.ycombinator.com/item?id=18566929