== null) return;

      this.drawTooltip_();
    },

    drawLineAtBottomOfChart_() {
      this.chartCtx_.strokeStyle = '#AAA';
      this.chartCtx_.moveTo(0, this.chartHeight_ - 0.5);
      this.chartCtx_.lineTo(this.chartWidth_, this.chartHeight_ - 0.5);
      this.chartCtx_.stroke();
    },

    drawTooltip_() {
      const tooltipData = this.opsTimingData_[this.currentBarMouseOverTarget_];
      const tooltipTitle = tooltipData.cmd_string;
      const tooltipTime = tooltipData.cmd_time.toFixed(4);

   