createTicker method
Registers and returns an inactive ticker that unregisters on disposal.
onDispose also runs when the ticker is disposed; framework ticker
providers use it to drop their own tracking references.
Implementation
Ticker createTicker(
TickerCallback onTick, {
String? debugLabel,
void Function(Ticker)? onDispose,
}) {
final ticker = Ticker._(
onTick,
this,
debugLabel: debugLabel,
onDispose: onDispose,
);
_managedTickers.add(ticker);
return ticker;
}