Move platform_window_mus_unittest to native_widget_mus_unittest

ui/views/mus/native_widget_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_NATIVE_WIDGET_MUS_H_
 #define UI_VIEWS_MUS_NATIVE_WIDGET_MUS_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 207 matching lines @@
   void OnHostCloseRequested(const aura::WindowTreeHost* host) override;
 
   // Overridden from mus::InputEventHandler:
   void OnWindowInputEvent(
       mus::Window* view,
       const ui::Event& event,
       std::unique_ptr<base::Callback<void(mus::mojom::EventResult)>>*
           ack_callback) override;
 
 private:
+  friend class NativeWidgetMusTest;
   class MusWindowObserver;
 
   ui::PlatformWindowDelegate* platform_window_delegate() {
     return window_tree_host();
   }
 
   void set_last_cursor(mus::mojom::Cursor cursor) { last_cursor_ = cursor; }
   void SetShowState(mus::mojom::ShowState show_state);
 
   void OnMusWindowVisibilityChanging(mus::Window* window);
@@ skipping 24 matching lines @@
   std::unique_ptr<aura::client::ScreenPositionClient> screen_position_client_;
   std::unique_ptr<wm::CursorManager> cursor_manager_;
   base::WeakPtrFactory<NativeWidgetMus> close_widget_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(NativeWidgetMus);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_MUS_NATIVE_WIDGET_MUS_H_