Get rid of the EnableClose() infrastructure in Widget.

ui/views/window/native_frame_view.h

 // Copyright (c) 2011 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_WINDOW_NATIVE_FRAME_VIEW_H_
 #define UI_VIEWS_WINDOW_NATIVE_FRAME_VIEW_H_
 #pragma once
 
 #include "ui/views/window/non_client_view.h"
 
 namespace views {
 
 class Widget;
 
 class VIEWS_EXPORT NativeFrameView : public NonClientFrameView {
  public:
   explicit NativeFrameView(Widget* frame);
   virtual ~NativeFrameView();
 
   // NonClientFrameView overrides:
   virtual gfx::Rect GetBoundsForClientView() const OVERRIDE;
   virtual gfx::Rect GetWindowBoundsForClientBounds(
       const gfx::Rect& client_bounds) const OVERRIDE;
   virtual int NonClientHitTest(const gfx::Point& point) OVERRIDE;
   virtual void GetWindowMask(const gfx::Size& size,
                              gfx::Path* window_mask) OVERRIDE;
-  virtual void EnableClose(bool enable) OVERRIDE;
   virtual void ResetWindowControls() OVERRIDE;
   virtual void UpdateWindowIcon() OVERRIDE;
 
   // View overrides:
 
   // Returns the client size. On Windows, this is the expected behavior for
   // native frames (see |NativeWidgetWin::WidgetSizeIsClientSize()|), while
   // other platforms currently always return client bounds from
   // |GetWindowBoundsForClientBounds()|.
   virtual gfx::Size GetPreferredSize() OVERRIDE;
 
  private:
   // Our containing frame.
   Widget* frame_;
 
   DISALLOW_COPY_AND_ASSIGN(NativeFrameView);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WINDOW_NATIVE_FRAME_VIEW_H_