Virtual destructors should have virtual keyword.

chrome/browser/ui/gtk/custom_button.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_CUSTOM_BUTTON_H_
 #define CHROME_BROWSER_UI_GTK_CUSTOM_BUTTON_H_
 #pragma once
 
 #include <gtk/gtk.h>
 
@@ skipping 20 matching lines @@
 class CustomDrawButtonBase : public NotificationObserver {
  public:
   // If the images come from ResourceBundle rather than the theme provider,
   // pass in NULL for |theme_provider|.
   CustomDrawButtonBase(GtkThemeService* theme_provider,
                        int normal_id,
                        int pressed_id,
                        int hover_id,
                        int disabled_id);
 
-  ~CustomDrawButtonBase();
+  virtual ~CustomDrawButtonBase();
 
   // Flip the image horizontally. Not to be used for RTL/LTR reasons. (In RTL
   // mode, this will unflip the image.)
   void set_flipped(bool flipped) { flipped_ = flipped; }
 
   // Returns the dimensions of the first surface.
   int Width() const;
   int Height() const;
 
   gboolean OnExpose(GtkWidget* widget, GdkEventExpose* e, gdouble hover_state);
@@ skipping 95 matching lines @@
 
   // As above, but uses an arbitrary GtkImage rather than a stock icon. This
   // constructor takes ownership of |native_widget|.
   CustomDrawButton(GtkThemeService* theme_provider,
                    int normal_id,
                    int pressed_id,
                    int hover_id,
                    int disabled_id,
                    GtkWidget* native_widget);
 
-  ~CustomDrawButton();
+  virtual ~CustomDrawButton();
 
   void Init();
 
   // Flip the image horizontally. Not to be used for RTL/LTR reasons. (In RTL
   // mode, this will unflip the image.)
   void set_flipped(bool flipped) { button_base_.set_flipped(flipped); }
 
   GtkWidget* widget() const { return widget_.get(); }
 
   gfx::Rect bounds() const {
@@ skipping 50 matching lines @@
   // Our theme provider.
   GtkThemeService* theme_service_;
 
   // Used to listen for theme change notifications.
   NotificationRegistrar registrar_;
 
   DISALLOW_COPY_AND_ASSIGN(CustomDrawButton);
 };
 
 #endif  // CHROME_BROWSER_UI_GTK_CUSTOM_BUTTON_H_