async checkScreenshot(baseName, time=0.1) {
    await this.beforeScreenshot(time);

    return shaka.test.LayoutTests.checkScreenshot(
        /* element= */ this.videoContainer,
        this.prefix + '-' + baseName,
        this.minSimilarity);
  }
@param {string} baseName The base name of the screenshot.
@param {number=} time The time to seek to in the screenshot.  Defaults to
  0.1, when most of our tests will be showing cues (timed 0-1).
@return {!Promise}