Virtual destructors should have virtual keyword.

chrome/browser/ui/gtk/download/download_item_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 CHROME_BROWSER_UI_GTK_DOWNLOAD_DOWNLOAD_ITEM_GTK_H_
 #define CHROME_BROWSER_UI_GTK_DOWNLOAD_DOWNLOAD_ITEM_GTK_H_
 #pragma once
 
 #include <gtk/gtk.h>
 
@@ skipping 27 matching lines @@
 
 class DownloadItemGtk : public DownloadItem::Observer,
                         public ui::AnimationDelegate,
                         public NotificationObserver {
  public:
   // DownloadItemGtk takes ownership of |download_item_model|.
   DownloadItemGtk(DownloadShelfGtk* parent_shelf,
                   BaseDownloadItemModel* download_item_model);
 
   // Destroys all widgets belonging to this DownloadItemGtk.
-  ~DownloadItemGtk();
+  virtual ~DownloadItemGtk();
 
   // DownloadItem::Observer implementation.
   virtual void OnDownloadUpdated(DownloadItem* download);
   virtual void OnDownloadOpened(DownloadItem* download) { }
 
   // ui::AnimationDelegate implementation.
   virtual void AnimationProgressed(const ui::Animation* animation);
 
   // Overridden from NotificationObserver:
   virtual void Observe(NotificationType type,
@@ skipping 173 matching lines @@
 
   // For canceling an in progress icon request.
   CancelableRequestConsumerT<int, 0> icon_consumer_;
 
   // Indicates when the download has completed, so we don't redo
   // on-completion actions.
   bool download_complete_;
 };
 
 #endif  // CHROME_BROWSER_UI_GTK_DOWNLOAD_DOWNLOAD_ITEM_GTK_H_