Google open sourced chrome, it created it and helped to standardize the web and others to freely have a good base for a browsers ... It found a way to have all advantages without penalizing others.
This isn't a monopoly behaviour.
No. Making your sites work worse on other browsers is absolutely anti-competitive behavior. Making it so that you get first and last peeks at ad auctions is absolutely anti-competitive behavior. Open sourcing Chrome does not make up for that.