aura-mus: Implement stacking in DesktopWindowTreeHostMus.

services/ui/ws/access_policy_delegate.h

 // Copyright 2014 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 SERVICES_UI_WS_ACCESS_POLICY_DELEGATE_H_
 #define SERVICES_UI_WS_ACCESS_POLICY_DELEGATE_H_
 
 #include <vector>
 
 #include "base/containers/hash_tables.h"
@@ skipping 12 matching lines @@
   virtual bool HasRootForAccessPolicy(const ServerWindow* window) const = 0;
 
   // Returns true if |window| has been exposed to the client.
   virtual bool IsWindowKnownForAccessPolicy(
       const ServerWindow* window) const = 0;
 
   // Returns true if Embed(window) has been invoked on |window|.
   virtual bool IsWindowRootOfAnotherTreeForAccessPolicy(
       const ServerWindow* window) const = 0;
 
+  // Returns true if |window| was created by the window manager.
+  virtual bool IsWindowCreatedByWindowManager(
+      const ServerWindow* window) const = 0;
+
  protected:
   virtual ~AccessPolicyDelegate() {}
 };
 
 }  // namespace ws
 
 }  // namespace ui
 
 #endif  // SERVICES_UI_WS_ACCESS_POLICY_DELEGATE_H_