I agree with Matthew that the supposed problem this is solving doesn't seem to be an issue for the case where no one is logged in to Chrome. In addition it seem

I agree with Matthew that the supposed problem this is solving doesn't seem to be an issue for the case where no one is logged in to Chrome. In addition it seems to me as if it has a non-invasive solution: If A is signed in to Chrome, and the user then signs into gmail as B, sign A out of Chrome, perhaps with a notification telling them what to do.