If all Google wanted was GPL- and AGPL-free code, they're quite capable of assigning their own engineers / contractors to work on it rather than the more tortuous route of going via a 3rd party
There are a lot of tricks needed to make the above work, and details that you need to consult a lawyer and accountant for.
but if they develop it for internal usage only, then they don't get the added benefit of destroying the existing copylefted version!