Google open source policy. Even if you work on something with your own equipment, on your own time, and it doesn't relate to your work, it probably still relates to something Google does. Therefore Google asserts ownership over all work their employees produce and thus they have these disclaimers.
It's possible sometimes to get Google to disclaim ownership of stuff that's genuinely unrelated. There is a process. (Or was when I left.)
On the other hand, if you want to work on open source on company time or use the code at work (which may have been part of the point of writing it), being able to do so is nice.
The process still exists, but it's discouraged for open-source projects. On the other hand, most open-source projects don't care who owns the copyright.
