[Cleanup] Screen cleanup

ash/shell.h

Index: ash/shell.h
diff --git a/ash/shell.h b/ash/shell.h
index a452cd53ea473bf7e5d54b8df26ecba669c4cc16..7d87ea694b9311b2f3efe9846c7ec3e96ecda719 100644
--- a/ash/shell.h
+++ b/ash/shell.h
@@ -413,8 +413,6 @@ class ASH_EXPORT Shell
     return shelf_item_delegate_manager_.get();
   }
 
-  ScreenAsh* screen() { return screen_; }
-
   // Force the shelf to query for it's current visibility state.
   void UpdateShelfVisibility();
 
@@ -578,8 +576,6 @@ class ASH_EXPORT Shell
   // when the screen is initially created.
   static bool initially_hide_cursor_;
 
-  ScreenAsh* screen_;
-
   // When no explicit target display/RootWindow is given, new windows are
   // created on |scoped_target_root_window_| , unless NULL in
   // which case they are created on |target_root_window_|.