Now, many posts later, you are saying "we released" and "I've been given the authority" as if you were the one authorized to "release the copyright".
But previously you said someone else did. Did you get the authority in the time between the two comments? Who are you? Who at Google can verify that you have the authority to release Google code? What documentation of this is there? You say no paperwork is necessary? Is there an official list somewhere of which code Google legal/corporate has released? How does your term "copyright release" differ from placing something under a open source license? Usually 'releasing' copyright means placing something in the public domain. Are you using the common usage when you use the term "release". What about the 25% not 'released'? Did any of those represent code that had already been placed by the coder in a outside project? Were they informed afterwords to remove the code?
Here we have a coder who is contributing to a project who says the author of the code for copyright purposes is Google Incorporated. But he is not the legal representative of Google. What legal authority does he have to transfer ownership or determine contractual licensing terms of code owned by Google on their behalf? If he does have this authority, or it has been granted him by you or someone else, it has to be in writing or it means nothing. Yet you are saying it doesn't have to be documented anywhere?
Maybe this is authorized by the appropriate people at Google. Maybe not. Without any documentation of it, there's no legal bias for saying this © Google code is BSD licensed.