content: Remove views dependency.

ui/views/mus/native_widget_mus.h

Index: ui/views/mus/native_widget_mus.h
diff --git a/ui/views/mus/native_widget_mus.h b/ui/views/mus/native_widget_mus.h
index 2e50183eeb6e711085c4807a1523a922a807da34..38e493a93e037d6da06f8b2f024ec2924d53d264 100644
--- a/ui/views/mus/native_widget_mus.h
+++ b/ui/views/mus/native_widget_mus.h
@@ -43,6 +43,7 @@ enum class EventResult;
 
 namespace ui {
 class Event;
+class ViewProp;
 }
 
 namespace wm {
@@ -272,6 +273,7 @@ class VIEWS_MUS_EXPORT NativeWidgetMus
   std::unique_ptr<aura::client::WindowTreeClient> window_tree_client_;
   std::unique_ptr<aura::client::ScreenPositionClient> screen_position_client_;
   std::unique_ptr<wm::CursorManager> cursor_manager_;
+  std::unique_ptr<ui::ViewProp> prop_;
 
   base::WeakPtrFactory<NativeWidgetMus> close_widget_factory_;