static async computeObservedMetric(data) {
    const {processedNavigation} = data;

    return {
      timing: processedNavigation.timings.firstContentfulPaintAllFrames,
      timestamp: processedNavigation.timestamps.firstContentfulPaintAllFrames,
    };
  }
@param {LH.Artifacts.NavigationMetricComputationData} data
@return {Promise<LH.Artifacts.Metric>}