startBackgroundSync method
Starts background sync. Optionally set syncDaysBack to control how
many days of historical data to sync (from start of day, inclusive).
When null (the default), syncs all available history (full sync).
Implementation
@override
Future<bool> startBackgroundSync({int? syncDaysBack}) async {
final result = await _channel.invokeMethod<bool>('startBackgroundSync', {
if (syncDaysBack != null) 'syncDaysBack': syncDaysBack,
});
return result == true;
}