updateAriaLabel() {
    const LocIds = shaka.ui.Locales.Ids;
    if (this.isEnded() && this.video.duration) {
      this.button.ariaLabel = this.localization.resolve(LocIds.REPLAY);
    } else {
      const label = this.isPaused() ? LocIds.PLAY : LocIds.PAUSE;
      this.button.ariaLabel = this.localization.resolve(label);
    }
  }
Called when the button's aria label needs to change.
To be overridden by subclasses, if necessary