aura-mus: Implement stacking in DesktopWindowTreeHostMus.

ui/aura/mus/window_tree_client_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 UI_AURA_MUS_WINDOW_TREE_CLIENT_DELEGATE_H_
 #define UI_AURA_MUS_WINDOW_TREE_CLIENT_DELEGATE_H_
 
 #include <memory>
 #include <string>
 
 #include "services/service_manager/public/interfaces/interface_provider.mojom.h"
 #include "services/ui/public/interfaces/window_tree.mojom.h"
 #include "ui/aura/aura_export.h"
 
 namespace aura {
 
 class PropertyConverter;
 class Window;
 class WindowTreeClient;
 class WindowTreeHostMus;
+enum class ChangeType;
 
 namespace client {
 class CaptureClient;
 }
 
 // Interface implemented by an application using mus.
 class AURA_EXPORT WindowTreeClientDelegate {
  public:
   // Called when the application implementing this interface is embedded.
   // NOTE: this is only invoked if the WindowTreeClient is created with an
@@ skipping 24 matching lines @@
   // have no real effect. Generally when this is called clients should delete
   // the corresponding WindowTreeClient.
   virtual void OnLostConnection(WindowTreeClient* client) = 0;
 
   // Called when the WindowTreeClient receives an input event observed via
   // StartPointerWatcher(). |target| may be null for events that were sent to
   // windows owned by other processes.
   virtual void OnPointerEventObserved(const ui::PointerEvent& event,
                                       Window* target) = 0;
 
+  // Called during change completion. Implemented in testing delegates.
+  virtual void OnChangeCompleted(ChangeType type, bool success) {}
+
   // Mus expects a single CaptureClient is used for all WindowTreeHosts. This
   // returns it. GetCaptureClient() is called from the constructor.
   virtual client::CaptureClient* GetCaptureClient() = 0;
 
   virtual PropertyConverter* GetPropertyConverter() = 0;
 
  protected:
   virtual ~WindowTreeClientDelegate() {}
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_MUS_WINDOW_TREE_CLIENT_DELEGATE_H_