Move ShowState-related code from PlatformWindowMus to NativeWidgetMus

ui/views/mus/window_tree_host_mus.h

 // Copyright 2015 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_WINDOW_TREE_HOST_MUS_H_
 #define UI_VIEWS_MUS_WINDOW_TREE_HOST_MUS_H_
 
 #include "base/macros.h"
 #include "ui/aura/window_tree_host_platform.h"
 #include "ui/views/mus/mus_export.h"
@@ skipping 15 matching lines @@
 class PlatformWindowMus;
 
 class VIEWS_MUS_EXPORT WindowTreeHostMus : public aura::WindowTreeHostPlatform {
  public:
   WindowTreeHostMus(shell::Connector* connector,
                     NativeWidgetMus* native_widget,
                     mus::Window* window);
   ~WindowTreeHostMus() override;
 
   PlatformWindowMus* platform_window();
-  ui::PlatformWindowState show_state() const { return show_state_; }
 
  private:
   // aura::WindowTreeHostPlatform:
   void DispatchEvent(ui::Event* event) override;
   void OnClosed() override;
-  void OnWindowStateChanged(ui::PlatformWindowState new_state) override;
   void OnActivationChanged(bool active) override;
   void OnCloseRequest() override;
 
   NativeWidgetMus* native_widget_;
   std::unique_ptr<InputMethodMUS> input_method_;
-  ui::PlatformWindowState show_state_;
 
   DISALLOW_COPY_AND_ASSIGN(WindowTreeHostMus);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_MUS_WINDOW_TREE_HOST_MUS_H_