updateCurrentVariant(newVariant, fromAdaptation) {
    if (this.currentVariant_ == newVariant) {
      return;
    }

    this.currentVariant_ = newVariant;
    this.history_.push({
      timestamp: this.getNowInSeconds_(),
      id: newVariant.id,
      type: 'variant',
      fromAdaptation: fromAdaptation,
      bandwidth: newVariant.bandwidth,
    });
  }
Update the history to show that we are currently playing |newVariant|. If
we are already playing |newVariant|, this update will be ignored.

@param {shaka.extern.Variant} newVariant
@param {boolean} fromAdaptation