https://qooah.com/2012/06/26/%e8%b6%95%e5%9c%a8-google-io-2012-%e5%a4%a7%e6%9c%83%e5%89%8d%e8%a1%9d%e5%88%ba-nexus-7-%e8%a6%8f%e6%a0%bc%e5%a4%a7%e6%9b%9d%e5%85%89/