chartCtx_.restore();

      this.chartCtx_.fillStyle = '#222';
      this.chartCtx_.textBaseline = 'top';
      this.chartCtx_.font = '800 12px Arial';
      this.chartCtx_.fillText(tooltipTitle, left + 8, top + 8);

      this.chartCtx_.fillStyle = '#555';
      this.chartCtx_.textBaseline = 'top';
      this.chartCtx_.font = '400 italic 10px Arial';
      this.chartCtx_.fillText('Total: ' + tooltipTime + 'ms',
          left + 8, top + 22);
    },

    drawBars_() {
      const len = this.opsTimingData_.l