Update example_overview_map_with_scene.dart (#66)

* Update example_overview_map_with_scene.dart

* Update example_overview_map_with_scene.dart

Author: harish-kunchala

example/lib/example_overview_map_with_scene.dart

@@ -60,6 +60,7 @@ class _ExampleOverviewMapWithSceneState
           // Pass the overview map the corresponding scene view controller.
           OverviewMap.withSceneView(
             controllerProvider: () => _sceneViewController,
+            map: ArcGISMap.withBasemapStyle(BasemapStyle.arcGISImageryStandard),
           ),
         ],
       ),