Uh, no. None of them existed before Google. What did exist were two pieces of infrastructure (Webkit and the Linux kernel), and Google could've used both without open-sourcing the rest of the application, since the licenses allow it:

- Webkit is LGPL/BSD, so it can be linked to proprietary code without forcing its redistribution.

- The Linux kernel is GPL, but the license has never applied to userspace code, and everything "above" is either written by Google or non-copyleft open source code.

I think it's only reasonably for Google to contribute some after getting so much from open source projects, but that doesn't mean they didn't have the legal choice to do otherwise.