vicePixelRatio;

      this.chart_ = document.createElement('canvas');
      this.chartCtx_ = this.chart_.getContext('2d');
      Polymer.dom(this).appendChild(this.chart_);

      this.opsTimingData_ = [];

      this.chartWidth_ = 0;
      this.chartHeight_ = 0;
      this.requiresRedraw_ = true;

      this.currentBarMouseOverTarget_ = null;

      this.chart_.addEventListener('mousemove', this.onMouseMove_.bind(this));
      try {
        new ResizeObserver(this.onResize_.bind(this)).observe(this);
    