message: Add 3.x player support
  keymap (MixedPlayerAgent)
  outerWatchlater
  quickFavorite
diff: @@ -250,12 +250,20 @@ export class VideoPlayerV2Agent extends PlayerAgent {
  if (!this.nativeApi) {
  return null
  }
  + if (this.nativeApi.isMuted) {
  + return this.nativeApi.isMuted()
  + }
  return this.nativeApi.isMute()
  }
  changeVolume(change: number) {
  if (!this.nativeApi) {
  return null
  }
  + if (this.nativeApi.getVolume) {
  + const current = this.nativeApi.getVolume()
  + this.nativeApi.setVolume(current + change / 100)
  + return Math.round(this.nativeApi.getVolume() * 100)
  + }
  const current = this.nativeApi.volume()
  this.nativeApi.volume(current + change / 100)
  return Math.round(this.nativeApi.volume() * 100)
  