[Cleanup] Screen cleanup

ash/shell.h

Index: ash/shell.h
diff --git a/ash/shell.h b/ash/shell.h
index ff58e66372b4a004ad81c46deec72f43d585fe14..d2019f939ed3b1c1ba47dcb8f9809e75dc9d9170 100644
--- a/ash/shell.h
+++ b/ash/shell.h
@@ -414,8 +414,6 @@ 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();
 
@@ -582,8 +580,6 @@ 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_|.