If you're smart enough to use Github, you're smart enough to understand that "source code I can easily copy" does not mean "source code I am allowed to use if it is cool enough".
If there is no license attached, then standard US copyright applies to it. In short: all rights are reserved to the original author (Google Inc.) and you're not allowed to reproduce the text anywhere.
Of course, then you get into Fair Use and private use, and a million other legal conundrums. But, yeah, not open source.
