cabana: Fix visibility issue for a single data point in series (comma…

…ai#32749)

Fix visibility issue for a single data point in series
old-commit-hash: 38529c5

tools/cabana/chart/chart.cc

@@ -277,7 +277,7 @@ void ChartView::updateSeriesPoints() {
         }
         ((QScatterSeries *)s.series)->setMarkerSize(size);
       } else {
-        s.series->setPointsVisible(pixels_per_point > 20);
+        s.series->setPointsVisible(num_points == 1 || pixels_per_point > 20);
       }
     }
   }