I based my estimate on the Waymo going slower than other cars and the city speed limit in Toronto being 50 km/h, and I took a stab at the numbers. I think it was Beverly Blvd which the internet says has a speed limit of 35 mph = 56 kph at the time?
I was in the back seat so I couldn't judge the distance that well. I passed the other car in a second so I guessed that's how much ground I covered.