Well back then Makkah was under the Ottoman empire. Then Hijaz (West part of the Arabian Peninsuela i.e Makkah, Medina, Jeddah..etc) gained independance for a brief time in 1914. It was Ruled by Al-Ashraf (descendants of prophet Mohamed). While the Saudi kingdom was in Najd (Middle of the peninsula where Riyadh is) and the Eastern province (where the oil is

). Hijaz became under of the Saudi rule later around 1924.
Also I think when Ahead said "Sherif of Makkah" he probably doesn't mean an enforcer of law, but the decsendants of prophet Mohammed (through Hussain ibn Ali). Sherif means virtuous in Arabic. Other descendants are called Sadda (through Hassan ibn Ali), Sadda means masters. So descendants of prophet Mohammed are either Ashraf or Sadda and there are thousands of them all over the world.
Anyways I guess I was blabbering too much, if you want to know more don't hesitate