All table serve restaurants have them (ask when you make your reservations so they know that you will need one). They have them at the counter serve places as well, but there is never a guarantee that they won't all be used.
Also just know that if your child is sleeping when you get to the restaurant, they will not make you wake them and out of the stroller. This is the only time in which they will allow you to bring the stroller into the restaurant.