unscheduleTick method
Cancels the frame callback that was requested by scheduleTick, if any.
Calling this method when no tick is scheduled is harmless.
This method should not be called when shouldScheduleTick would return true if no tick was scheduled.
Implementation
@protected
void unscheduleTick() {
if (scheduled) {
SchedulerBinding.instance.cancelFrameCallbackWithId(_animationId!);
_animationId = null;
}
assert(!shouldScheduleTick);
}