WIP: simplified display management in ash

ui/aura/mus/mus_types.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_AURA_MUS_MUS_TYPES_H_
 #define UI_AURA_MUS_MUS_TYPES_H_
 
 #include <stdint.h>
 
 // Typedefs for the transport types. These typedefs match that of the mojom
@@ skipping 22 matching lines @@
 
   // The window was created by requesting a top level
   // (WindowTree::NewTopLevel()).
   // NOTE: in the window manager (the one responsible for actually creating the
   // real window) the window is of type TOP_LEVEL_IN_WM.
   TOP_LEVEL,
 
   // The window is a top level window in the window manager.
   TOP_LEVEL_IN_WM,
 
-  // The window is a display root for the window manager.
-  DISPLAY,
+  // The window is a display root for the window manager and was automatically
+  // by mus.
+  DISPLAY_AUTOMATICALLY_CREATED,
+
+  // The window is a display root for the window manager and was manually
+  // created.
+  DISPLAY_MANUALLY_CREATED,
 
   // The window was created locally.
   LOCAL,
 
   // Not one of the above. This means the window is visible to the client and
   // not one of the above values. Practically this means this client is the
   // window manager and the window was created by another client.
   OTHER,
 };
 
 }  // namespace ui
 
 #endif  // UI_AURA_MUS_MUS_TYPES_H_