add track information to data legend

app/assets/javascripts/monitoring/utils/multiple_time_series.js

@@ -65,9 +65,9 @@ function queryTimeSeries(query, graphWidth, graphHeight, graphHeightOffset, maxV
 
     const timeSeriesMetricLabel = timeSeries.metric[Object.keys(timeSeries.metric)[0]];
     const seriesCustomizationData = query.series != null &&
-                                    _.findWhere(query.series[0].when,
-                                    { value: timeSeriesMetricLabel });
-    if (seriesCustomizationData != null) {
+      _.findWhere(query.series[0].when, { value: timeSeriesMetricLabel });
+
+    if (seriesCustomizationData) {
       metricTag = seriesCustomizationData.value || timeSeriesMetricLabel;
       [lineColor, areaColor] = pickColor(seriesCustomizationData.color);
     } else {
@@ -75,6 +75,10 @@ function queryTimeSeries(query, graphWidth, graphHeight, graphHeightOffset, maxV
       [lineColor, areaColor] = pickColor();
     }
 
+    if (query.track) {
+      metricTag += ` - track: ${query.track}`;
+    }
+
     return {
       linePath: lineFunction(timeSeries.values),
       areaPath: areaFunction(timeSeries.values),