Removes code using mus client lib

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 "services/service_manager/public/cpp/connector.h"
-#include "ui/aura/window_tree_host_platform.h"
-#include "ui/views/mus/mus_export.h"
-
-namespace ui {
-class Window;
-}
-
-namespace views {
-
-class NativeWidgetMus;
-
-class VIEWS_MUS_EXPORT WindowTreeHostMus : public aura::WindowTreeHostPlatform {
- public:
-  WindowTreeHostMus(NativeWidgetMus* native_widget, ui::Window* window);
-  ~WindowTreeHostMus() override;
-  NativeWidgetMus* native_widget() { return native_widget_; }
-
- private:
-  // aura::WindowTreeHostPlatform:
-  void DispatchEvent(ui::Event* event) override;
-  void OnClosed() override;
-  void OnActivationChanged(bool active) override;
-  void OnCloseRequest() override;
-  gfx::ICCProfile GetICCProfileForCurrentDisplay() override;
-
-  NativeWidgetMus* native_widget_;
-
-  DISALLOW_COPY_AND_ASSIGN(WindowTreeHostMus);
-};
-
-}  // namespace views
-
-#endif  // UI_VIEWS_MUS_WINDOW_TREE_HOST_MUS_H_