Dashboard charts: display sparklines of related timeseries in a tab strip.

dashboard/dashboard/elements/report-page.html

Index: dashboard/dashboard/elements/report-page.html
diff --git a/dashboard/dashboard/elements/report-page.html b/dashboard/dashboard/elements/report-page.html
index 59bd553d07ba9d8d3dfca046f51f05bbd90354fc..e6f624043a6d39bc3724154b4879107e84f8c921 100644
--- a/dashboard/dashboard/elements/report-page.html
+++ b/dashboard/dashboard/elements/report-page.html
@@ -67,6 +67,7 @@ found in the LICENSE file.
 
       listeners: {
         populateTestPicker: 'populateTestPicker_',
+        promoteSparkLine: 'promoteSparkLine_',
       },
 
       properties: {
@@ -152,6 +153,11 @@ found in the LICENSE file.
         await this.testPicker.setCurrentSelectedPath(event.detail.testPath);
       },
 
+      promoteSparkLine_(event) {
+        this.addChart(event.detail.testpaths.map(t =>
+            new d.SeriesGroup(t.testpath, [t.testpath], [])));
+      },
+
       /**
        * On 'uriload' event, adds charts from the current query parameters.
        * @param {Object} event Event object.
@@ -284,7 +290,7 @@ found in the LICENSE file.
        * When the revision range changes for one graph, update the rest of
        * the graphs and the URI.
        */
-      onRevisionRangeChanged(_, event) {
+      onRevisionRangeChanged(event) {
         const onRevisionRangeChangedMark = tr.b.Timing.mark(
             'report-page', 'onRevisionRangeChanged');
         for (let i = 0; i < this.charts.length; i++) {