I might be reading too much into this, but it looks like we're calculating the probability of two made shots followed by a missed shot. Otherwise we wouldn't know that the streak has ended, and this player could have made more that two consecutive shots.
So the probability of exactly two consecutive made shots = 0.9 * 0.9 * 0.1 = 0.081.
So the probability of exactly two consecutive made shots = 0.9 * 0.9 * 0.1 = 0.081.