Virtual destructors should have virtual keyword.

chrome/browser/ui/gtk/download/download_shelf_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_SHELF_GTK_H_
 #define CHROME_BROWSER_UI_GTK_DOWNLOAD_DOWNLOAD_SHELF_GTK_H_
 #pragma once
 
 #include <gtk/gtk.h>
 
@@ skipping 20 matching lines @@
 class Point;
 }
 
 class DownloadShelfGtk : public DownloadShelf,
                          public NotificationObserver,
                          public SlideAnimatorGtk::Delegate,
                          public MessageLoopForUI::Observer {
  public:
   explicit DownloadShelfGtk(Browser* browser, gfx::NativeView view);
 
-  ~DownloadShelfGtk();
+  virtual ~DownloadShelfGtk();
 
   // DownloadShelf implementation.
   virtual void AddDownload(BaseDownloadItemModel* download_model);
   virtual bool IsShowing() const;
   virtual bool IsClosing() const;
   virtual void Show();
   virtual void Close();
   virtual Browser* browser() const;
 
   // SlideAnimatorGtk::Delegate implementation.
@@ skipping 90 matching lines @@
   // True if the mouse is within the shelf's bounds, as of the last mouse event
   // we received.
   bool mouse_in_shelf_;
 
   ScopedRunnableMethodFactory<DownloadShelfGtk> auto_close_factory_;
 
   friend class DownloadItemGtk;
 };
 
 #endif  // CHROME_BROWSER_UI_GTK_DOWNLOAD_DOWNLOAD_SHELF_GTK_H_