Virtual destructors should have virtual keyword.

chrome/browser/ui/cocoa/notifications/balloon_view_bridge.h

 // Copyright (c) 2010 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_COCOA_NOTIFICATIONS_BALLOON_VIEW_BRIDGE_H_
 #define CHROME_BROWSER_UI_COCOA_NOTIFICATIONS_BALLOON_VIEW_BRIDGE_H_
 #pragma once
 
 #include "chrome/browser/notifications/balloon.h"
 
 @class BalloonController;
 class BalloonHost;
 namespace gfx {
 class Size;
 }
 
 // Bridges from the cross-platform BalloonView interface to the Cocoa
 // controller which will draw the view on screen.
 class BalloonViewBridge : public BalloonView {
  public:
   BalloonViewBridge();
-  ~BalloonViewBridge();
+  virtual ~BalloonViewBridge();
 
   // BalloonView interface.
   virtual void Show(Balloon* balloon);
   virtual void Update();
   virtual void RepositionToBalloon();
   virtual void Close(bool by_user);
   virtual gfx::Size GetSize() const;
   virtual BalloonHost* GetHost() const;
 
  private:
   // Weak pointer to the balloon controller which manages the UI.
   // This object cleans itself up when its windows close.
   BalloonController* controller_;
 
   DISALLOW_COPY_AND_ASSIGN(BalloonViewBridge);
 };
 
 #endif  // CHROME_BROWSER_UI_COCOA_NOTIFICATIONS_BALLOON_VIEW_BRIDGE_H_