src/vs/editor/common/model/textModel.ts/ModelDecorationOverviewRulerOptions/getColor
class ModelDecorationOverviewRulerOptions:	public getColor(theme: IColorTheme): string {
		if (!this._resolvedColor) {
			if (theme.type !== 'light' && this.darkColor) {
				this._resolvedColor = this._resolveColor(this.darkColor, theme);
			} else {
				this._resolvedColor = this._resolveColor(this.color, theme);
			}
		}
		return this._resolvedColor;
	}