YOU GAVE THEM YOUR PERMISSION.
Maybe, in the future, read the TOS and Privacy Policies rather than just pressing accept and acting offended when they do EXACTLY what they said they'd do.
Had you done that, you'd also know exactly who has access to that information and, if you read when they notify you of policy updates, who will have access in the future.
Why is this so hard to understand for people? Gmail is not free, you are paying with the information gleaned from it. If you aren't ok with that, start shelling out money.