updateCurrentText(newText, fromAdaptation) {
    if (this.currentText_ == newText) {
      return;
    }

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

@param {shaka.extern.Stream} newText
@param {boolean} fromAdaptation