) {
      this.chartCtx_.clearRect(0, 0, this.chartWidth_, this.chartHeight_);
    },

    showNoTimingDataMessage_() {
      this.chartCtx_.font = '800 italic 14px Arial';
      this.chartCtx_.fillStyle = '#333';
      this.chartCtx_.textAlign = 'center';
      this.chartCtx_.textBaseline = 'middle';
      this.chartCtx_.fillText('No timing data available.',
          this.chartWidth_ * 0.5, this.chartHeight_ * 0.5);
    },

    collapseOpsToTimingBuckets_(ops) {
      const opsTimingDataIndexHash_ = {};
 