Get rid of the EnableClose() infrastructure in Widget.

ui/views/widget/native_widget_gtk.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_WIDGET_NATIVE_WIDGET_GTK_H_
 #define UI_VIEWS_WIDGET_NATIVE_WIDGET_GTK_H_
 #pragma once
 
 #include <gtk/gtk.h>
 
@@ skipping 172 matching lines @@
   virtual gfx::Rect GetWindowScreenBounds() const OVERRIDE;
   virtual gfx::Rect GetClientAreaScreenBounds() const OVERRIDE;
   virtual gfx::Rect GetRestoredBounds() const OVERRIDE;
   virtual void SetBounds(const gfx::Rect& bounds) OVERRIDE;
   virtual void SetSize(const gfx::Size& size) OVERRIDE;
   virtual void MoveAbove(gfx::NativeView native_view) OVERRIDE;
   virtual void MoveToTop() OVERRIDE;
   virtual void SetShape(gfx::NativeRegion shape) OVERRIDE;
   virtual void Close() OVERRIDE;
   virtual void CloseNow() OVERRIDE;
-  virtual void EnableClose(bool enable) OVERRIDE;
   virtual void Show() OVERRIDE;
   virtual void Hide() OVERRIDE;
   virtual void ShowMaximizedWithBounds(
       const gfx::Rect& restored_bounds) OVERRIDE;
   virtual void ShowWithWindowState(ui::WindowShowState window_state) OVERRIDE;
   virtual bool IsVisible() const OVERRIDE;
   virtual void Activate() OVERRIDE;
   virtual void Deactivate() OVERRIDE;
   virtual bool IsActive() const OVERRIDE;
   virtual void SetAlwaysOnTop(bool always_on_top) OVERRIDE;
@@ skipping 262 matching lines @@
   bool is_menu_;
 
   scoped_ptr<ui::GtkSignalRegistrar> signal_registrar_;
 
   DISALLOW_COPY_AND_ASSIGN(NativeWidgetGtk);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WIDGET_NATIVE_WIDGET_GTK_H_