Haven't had a change to review it yet but seems to be they retired Google Code in preparation for this, not because they were acquiescing the market to Github.
They describe it as "fully-featured private Git repositories" so not a replacement for Google code. Also it's pretty inconceivable they'd retire Google Code early, forcing repos to move to a competitor, then introduce a new public service.
https://cloud.google.com/source-repositories/
Haven't had a change to review it yet but seems to be they retired Google Code in preparation for this, not because they were acquiescing the market to Github.