onTouchEnd_(event) {
    // Only proceed if controls are visible.
    if (!this.controls.isOpaque()) {
      return;
    }

    // If user scrolled, don't handle as a tap.
    if (this.hasMoved_) {
      return;
    }

    // If any settings menus are open, this tap closes them instead of toggling
    // play/seek.
    if (this.controls.anySettingsMenusAreOpen()) {
      event.preventDefault();
      this.controls.hideSettingsMenus();
      return;
    }

    // Normal tap logic (single vs double tap).
    if (this.controls.getConfig().tapSeekDistance > 0) {
      event.preventDefault();
      this.onSeekButtonClick_();
    }
  }
Called when the user lifts the finger from the screen.
If we haven't moved beyond the threshold, treat it as a tap.
@param {!TouchEvent} event
@private