The google API has moved from code.google.com to github, and the new API is totally different from what this module assumes.

https://github.com/google/google-api-php-client

It's still possible to get the old API from code.google.com, but you have to

svn checkout http://google-api-php-client.googlecode.com/svn/trunk/ google-api-php-client

For now, perhaps update the instructions?