Gameplay Question to Solve a Bet...can an official Riot member help me out?

Okay everyone, I have some friends who are "1000%" certain that the Dragon Counters (picture link for example, taken from a reddit post,) actually automatically update when the enemy team KILLS the dragon. While this may be so, I'm pretty sure out of fairness, it actually only updates when they kill the dragon AND one of the enemy is or becomes visible after the fact. (e.g. All enemy team MIA, enemy team kills drag, enemy team comes out of fog of war and hey, they have a shiny new buff.) Understand? Any Official Riot employees like to put my friends where they belong?