It is time.

ui/views/widget/widget_deletion_observer.cc

-// Copyright (c) 2013 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/widget/widget_deletion_observer.h"
-
-#include "ui/views/widget/widget.h"
-
-namespace views {
-
-WidgetDeletionObserver::WidgetDeletionObserver(Widget* widget)
-    : widget_(widget) {
-  if (widget_)
-    widget_->AddObserver(this);
-}
-
-WidgetDeletionObserver::~WidgetDeletionObserver() {
-  CleanupWidget();
-}
-
-void WidgetDeletionObserver::OnWidgetDestroying(Widget* widget) {
-  CleanupWidget();
-}
-
-void WidgetDeletionObserver::CleanupWidget() {
-  if (widget_) {
-    widget_->RemoveObserver(this);
-    widget_ = NULL;
-  }
-}
-
-}  // namespace views