ui: Fix tooltip rendering

Bug: 208839043
Change-Id: I8c4b04c5091c8cb6b77cb7cc8fbf306c5eb0fb63
diff --git a/ui/src/frontend/track.ts b/ui/src/frontend/track.ts
index f319614..5cd1e9b 100644
--- a/ui/src/frontend/track.ts
+++ b/ui/src/frontend/track.ts
@@ -197,7 +197,7 @@
       const yOffsetPx = textMetrics.fontBoundingBoxAscent +
           textMetrics.fontBoundingBoxDescent +
           text2Metrics.fontBoundingBoxAscent;
-      ctx.fillText(text, x + paddingPx, y + paddingPx + yOffsetPx);
+      ctx.fillText(text2, x + paddingPx, y + paddingPx + yOffsetPx);
     }
   }