mus: Use TooltipManagerAura in NativeWidgetMus.

ui/views/mus/screen_mus_delegate.h

Index: ui/views/mus/screen_mus_delegate.h
diff --git a/ui/views/mus/screen_mus_delegate.h b/ui/views/mus/screen_mus_delegate.h
index 2ae48373b525a51d7ee8f217662aacf089072dd0..cdba900ebb08b30538447eb0cf230f93cac22675 100644
--- a/ui/views/mus/screen_mus_delegate.h
+++ b/ui/views/mus/screen_mus_delegate.h
@@ -11,6 +11,10 @@ namespace gfx {
 class Point;
 }
 
+namespace ui {
+class Window;
+}
+
 namespace views {
 
 // Screen implementation backed by ui::mojom::DisplayManager.
@@ -20,7 +24,9 @@ class VIEWS_MUS_EXPORT ScreenMusDelegate {
 
   virtual gfx::Point GetCursorScreenPoint() = 0;
 
-protected:
+  virtual ui::Window* GetWindowAtScreenPoint(const gfx::Point& point) = 0;
+
+ protected:
   virtual ~ScreenMusDelegate() {}
 };