Get rid of the EnableClose() infrastructure in Widget.

ui/views/window/custom_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_CUSTOM_FRAME_VIEW_H_
 #define UI_VIEWS_WINDOW_CUSTOM_FRAME_VIEW_H_
 #pragma once
 
 #include "ui/views/widget/widget.h"
 #include "ui/views/window/non_client_view.h"
@@ skipping 23 matching lines @@
   explicit CustomFrameView(Widget* frame);
   virtual ~CustomFrameView();
 
   // Overridden from NonClientFrameView:
   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:
   virtual void OnPaint(gfx::Canvas* canvas) OVERRIDE;
   virtual void Layout() OVERRIDE;
   virtual gfx::Size GetPreferredSize() OVERRIDE;
 
   // ButtonListener implementation:
   virtual void ButtonPressed(Button* sender, const views::Event& event)
@@ skipping 63 matching lines @@
   // Initialize various static resources.
   static void InitClass();
   static gfx::Font* title_font_;
 
   DISALLOW_COPY_AND_ASSIGN(CustomFrameView);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WINDOW_CUSTOM_FRAME_VIEW_H_