Virtual destructors should have virtual keyword.

chrome/browser/ui/gtk/tab_contents_drag_source.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_TAB_CONTENTS_DRAG_SOURCE_H_
 #define CHROME_BROWSER_UI_GTK_TAB_CONTENTS_DRAG_SOURCE_H_
 #pragma once
 
 #include <gtk/gtk.h>
 
@@ skipping 11 matching lines @@
 class SkBitmap;
 class TabContents;
 class TabContentsView;
 struct WebDropData;
 
 // TabContentsDragSource takes care of managing the drag from a TabContents
 // with Gtk.
 class TabContentsDragSource : public MessageLoopForUI::Observer {
  public:
   explicit TabContentsDragSource(TabContentsView* tab_contents_view);
-  ~TabContentsDragSource();
+  virtual ~TabContentsDragSource();
 
   TabContents* tab_contents() const;
 
   // Starts a drag for the tab contents this TabContentsDragSource was
   // created for.
   void StartDragging(const WebDropData& drop_data,
                      WebKit::WebDragOperationsMask allowed_ops,
                      GdkEventButton* last_mouse_down,
                      const SkBitmap& image,
                      const gfx::Point& image_offset);
@@ skipping 58 matching lines @@
   // an OwnedWidgetGtk because the GtkWindow initialization code sinks
   // the reference.
   GtkWidget* drag_icon_;
 
   ui::GtkSignalRegistrar signals_;
 
   DISALLOW_COPY_AND_ASSIGN(TabContentsDragSource);
 };
 
 #endif  // CHROME_BROWSER_UI_GTK_TAB_CONTENTS_DRAG_SOURCE_H_