Converts WindowTreeClientTest to be in terms of aura

ui/views/mus/mus_client.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_VIEWS_MUS_MUS_CLIENT_H_
 #define UI_VIEWS_MUS_MUS_CLIENT_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 92 matching lines @@
 
   MusClient(
       service_manager::Connector* connector,
       const service_manager::Identity& identity,
       scoped_refptr<base::SingleThreadTaskRunner> io_task_runner = nullptr);
 
   // aura::WindowTreeClientDelegate:
   void OnEmbed(
       std::unique_ptr<aura::WindowTreeHostMus> window_tree_host) override;
   void OnLostConnection(aura::WindowTreeClient* client) override;
-  void OnEmbedRootDestroyed(aura::Window* root) override;
+  void OnEmbedRootDestroyed(aura::WindowTreeHostMus* window_tree_host) override;
   void OnPointerEventObserved(const ui::PointerEvent& event,
                               aura::Window* target) override;
   aura::client::CaptureClient* GetCaptureClient() override;
   aura::PropertyConverter* GetPropertyConverter() override;
 
   // ScreenMusDelegate:
   void OnWindowManagerFrameValuesChanged() override;
   gfx::Point GetCursorScreenPoint() override;
   aura::Window* GetWindowAtScreenPoint(const gfx::Point& point) override;
 
@@ skipping 19 matching lines @@
   std::unique_ptr<PointerWatcherEventRouter2> pointer_watcher_event_router_;
 
   std::unique_ptr<aura::MusContextFactory> compositor_context_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(MusClient);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_MUS_MUS_CLIENT_H_