This subchapter applies only to a county having:
(1) a population of:
(A) at least 1.2 million; or
(B) at least 830,000 and not more than 870,000; and
(2) a countywide hospital district that:
(A) has taxes imposed and collected by the commissioners court of the county; and
(B) has teaching hospital facilities affiliated with a state-owned or private medical school.