FWIW, it looks like that's a test case -- it is not part of Chrome itself. They most likely just wanted an example of a third-party website, and could have used any non-Google site there.
There's no smoking gun here, but I don't think that concern might be dismissed out of hand. It might be good to see what Yahoo's take on this. This could even evolve into participation by the US Attorney General. I'd like to know more, either way. Like if Yahoo was independently added to the list at a later date, or if it was there from the start?