WidgetDelegateView is its own contents view.

ash/mus/non_client_frame_controller.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 ASH_MUS_NON_CLIENT_FRAME_CONTROLLER_H_
 #define ASH_MUS_NON_CLIENT_FRAME_CONTROLLER_H_
 
 #include <stdint.h>
 
 #include "ash/mus/frame/detached_title_area_renderer_host.h"
@@ skipping 38 matching lines @@
                            ui::Window* window,
                            ui::WindowManagerClient* window_manager_client);
   ~NonClientFrameController() override;
 
   // DetachedTitleAreaRendererHost:
   void OnDetachedTitleAreaRendererDestroyed(
       DetachedTitleAreaRenderer* renderer) override;
 
   // views::WidgetDelegateView:
   base::string16 GetWindowTitle() const override;
-  views::View* GetContentsView() override;
   bool CanResize() const override;
   bool CanMaximize() const override;
   bool CanMinimize() const override;
   bool ShouldShowWindowTitle() const override;
   views::ClientView* CreateClientView(views::Widget* widget) override;
 
   // ui::WindowObserver:
   void OnTreeChanged(const TreeChangeParams& params) override;
   void OnWindowSharedPropertyChanged(
       ui::Window* window,
@@ skipping 15 matching lines @@
   // kRendererParentTitleArea_Property set.
   DetachedTitleAreaRenderer* detached_title_area_renderer_ = nullptr;
 
   DISALLOW_COPY_AND_ASSIGN(NonClientFrameController);
 };
 
 }  // namespace mus
 }  // namespace ash
 
 #endif  // ASH_MUS_NON_CLIENT_FRAME_CONTROLLER_H_