Google does not even register the domains for themselves nor do they have a say in what gets registered. They use a service called Mark Monitor which has a service for registering a name with all the TLDs including the country ones. ICANN is a big player and the specific country that TLD belongs to has a role in picking a TLD.
Here are some wikipedia articles:
http://en.wikipedia.org/wiki/Top-level_domain
http://en.wikipedia.org/wiki/ICANN