Just seen Chelsea's equaliser against Cardiff. Foul on goalkeeper. He's in possession of the ball, whether he bounces it or not. In fact, he's in possession until he realises it to open play, and that is when he touches it with his feet, whether walking along with it or kicking it upfield.
Famously, George Best kicked a ball out of the air that Gordon Banks had thrown up to drop-kick the ball upfield, in a Rep of Ireland v England match, many years ago. Best scored from it. No goal. Foul on keeper, under the same rule.