I can confirm that Google was using Perforce for version control extensively, at least through 2008. I think it was somehow customized, but I definitely have lingering muscle memory around “p4 sync” and “p4 submit”.
I was on an internal tools team doing distinctly unsexy LAMP-stack work, but all the documentation I ever saw talked about perforce/p4.
I was on an internal tools team doing distinctly unsexy LAMP-stack work, but all the documentation I ever saw talked about perforce/p4.