Add scrolling gameplay visualisation mode to latency certifier

osu.Game/Screens/Utility/LatencyArea.cs

@@ -108,6 +108,20 @@ namespace osu.Game.Screens.Utility
                         };
                         break;
 
+                    case LatencyVisualMode.ScrollingGameplay:
+                        visualContent.Children = new Drawable[]
+                        {
+                            new ScrollingGameplay
+                            {
+                                RelativeSizeAxes = Axes.Both,
+                            },
+                            new LatencyCursorContainer
+                            {
+                                RelativeSizeAxes = Axes.Both,
+                            },
+                        };
+                        break;
+
                     default:
                         throw new ArgumentOutOfRangeException();
                 }