Converts WindowTreeClientTest to be in terms of aura

ui/aura/mus/window_port_mus.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_WINDOW_PORT_MUS_H_
 #define UI_AURA_MUS_WINDOW_PORT_MUS_H_
 
 #include <stdint.h>
 
 #include <string>
@@ skipping 195 matching lines @@
       std::unique_ptr<SurfaceInfo> surface_info) override;
   void DestroyFromServer() override;
   void AddTransientChildFromServer(WindowMus* child) override;
   void RemoveTransientChildFromServer(WindowMus* child) override;
   ChangeSource OnTransientChildAdded(WindowMus* child) override;
   ChangeSource OnTransientChildRemoved(WindowMus* child) override;
   std::unique_ptr<WindowMusChangeData> PrepareForServerBoundsChange(
       const gfx::Rect& bounds) override;
   std::unique_ptr<WindowMusChangeData> PrepareForServerVisibilityChange(
       bool value) override;
+  void PrepareForDestroy() override;
   void PrepareForTransientRestack(WindowMus* window) override;
   void OnTransientRestackDone(WindowMus* window) override;
   void NotifyEmbeddedAppDisconnected() override;
 
   // WindowPort:
   void OnPreInit(Window* window) override;
   void OnDeviceScaleFactorChanged(float device_scale_factor) override;
   void OnWillAddChild(Window* child) override;
   void OnWillRemoveChild(Window* child) override;
   void OnWillMoveChild(size_t current_index, size_t dest_index) override;
@@ skipping 16 matching lines @@
   std::unique_ptr<SurfaceInfo> surface_info_;
 
   ui::mojom::Cursor predefined_cursor_ = ui::mojom::Cursor::CURSOR_NULL;
 
   DISALLOW_COPY_AND_ASSIGN(WindowPortMus);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_MUS_WINDOW_PORT_MUS_H_