Changes ScreenMusDelegate::GetWindowAtScreenPoint to return aura::Window

ui/views/mus/window_manager_connection.h

Index: ui/views/mus/window_manager_connection.h
diff --git a/ui/views/mus/window_manager_connection.h b/ui/views/mus/window_manager_connection.h
index e8aef937c6eb352645cb2bd8b8078b7ff810b772..01d853e8991264b652df08c316d6408b87e3a5f6 100644
--- a/ui/views/mus/window_manager_connection.h
+++ b/ui/views/mus/window_manager_connection.h
@@ -94,6 +94,9 @@ class VIEWS_MUS_EXPORT WindowManagerConnection
       const service_manager::Identity& identity,
       scoped_refptr<base::SingleThreadTaskRunner> task_runner);
 
+  // Exposed for tests.
+  ui::Window* GetUiWindowAtScreenPoint(const gfx::Point& point);
+
   // ui::WindowTreeClientDelegate:
   void OnEmbed(ui::Window* root) override;
   void OnLostConnection(ui::WindowTreeClient* client) override;
@@ -104,7 +107,7 @@ class VIEWS_MUS_EXPORT WindowManagerConnection
   // ScreenMusDelegate:
   void OnWindowManagerFrameValuesChanged() override;
   gfx::Point GetCursorScreenPoint() override;
-  ui::Window* GetWindowAtScreenPoint(const gfx::Point& point) override;
+  aura::Window* GetWindowAtScreenPoint(const gfx::Point& point) override;
 
   // ui:OSExchangeDataProviderFactory::Factory:
   std::unique_ptr<OSExchangeData::Provider> BuildProvider() override;