initPlayer method
Starts the video playback.
Implementation
@override
Future<int> initPlayer(String url) async {
final int textureId = _textureCounter++;
ui.platformViewRegistry.registerViewFactory(
'gumlet-web-player-$textureId',
(int viewId) => IFrameElement()
..src = url
..style.border = 'none');
return textureId;
}