Get rid of the EnableClose() infrastructure in Widget.

ui/views/window/native_frame_view.cc

 // 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.
 
 #include "ui/views/window/native_frame_view.h"
 
 #include "ui/views/widget/native_widget.h"
 #include "ui/views/widget/widget.h"
 
 #if defined(OS_WIN) && !defined(USE_AURA)
@@ skipping 37 matching lines @@
 
 int NativeFrameView::NonClientHitTest(const gfx::Point& point) {
   return frame_->client_view()->NonClientHitTest(point);
 }
 
 void NativeFrameView::GetWindowMask(const gfx::Size& size,
                                     gfx::Path* window_mask) {
   // Nothing to do, we use the default window mask.
 }
 
-void NativeFrameView::EnableClose(bool enable) {
-  // Nothing to do, handled automatically by Window.
-}
-
 void NativeFrameView::ResetWindowControls() {
   // Nothing to do.
 }
 
 void NativeFrameView::UpdateWindowIcon() {
   // Nothing to do.
 }
 
 gfx::Size NativeFrameView::GetPreferredSize() {
   return frame_->client_view()->GetPreferredSize();
 }
 
 }  // namespace views