Remove dependency on ui from view_manager.

mojo/services/public/cpp/view_manager/view_observer.h

Index: mojo/services/public/cpp/view_manager/view_observer.h
diff --git a/mojo/services/public/cpp/view_manager/view_observer.h b/mojo/services/public/cpp/view_manager/view_observer.h
index 1a2ab7e2283b176a43e499daaa16b258a6d54a59..ab52666ff8699171923d4a6b71e02f062d54a57a 100644
--- a/mojo/services/public/cpp/view_manager/view_observer.h
+++ b/mojo/services/public/cpp/view_manager/view_observer.h
@@ -12,10 +12,6 @@
 #include "mojo/services/public/cpp/view_manager/view.h"
 #include "mojo/services/public/interfaces/input_events/input_events.mojom.h"
 
-namespace gfx {
-class Rect;
-}
-
 namespace mojo {
 
 class View;
@@ -54,11 +50,11 @@ class ViewObserver {
   virtual void OnViewDestroyed(View* view) {}
 
   virtual void OnViewBoundsChanging(View* view,
-                                    const gfx::Rect& old_bounds,
-                                    const gfx::Rect& new_bounds) {}
+                                    const Rect& old_bounds,
+                                    const Rect& new_bounds) {}
   virtual void OnViewBoundsChanged(View* view,
-                                   const gfx::Rect& old_bounds,
-                                   const gfx::Rect& new_bounds) {}
+                                   const Rect& old_bounds,
+                                   const Rect& new_bounds) {}
 
   virtual void OnViewFocusChanged(View* gained_focus, View* lost_focus) {}