Reapply and fix r73019. BalloonViewImpl has a different implemementation on

chrome/browser/ui/gtk/notifications/balloon_view_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.
 
 // Draws the view for the balloons.
 
 #ifndef CHROME_BROWSER_UI_GTK_NOTIFICATIONS_BALLOON_VIEW_GTK_H_
 #define CHROME_BROWSER_UI_GTK_NOTIFICATIONS_BALLOON_VIEW_GTK_H_
 #pragma once
 
@@ skipping 23 matching lines @@
 }
 
 // A balloon view is the UI component for desktop notification toasts.
 // It draws a border, and within the border an HTML renderer.
 class BalloonViewImpl : public BalloonView,
                         public MenuGtk::Delegate,
                         public NotificationObserver,
                         public ui::AnimationDelegate {
  public:
   explicit BalloonViewImpl(BalloonCollection* collection);
-  ~BalloonViewImpl();
+  virtual ~BalloonViewImpl();
 
   // 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;
 
   // MenuGtk::Delegate interface.
@@ skipping 77 matching lines @@
   // Is the menu currently showing?
   bool menu_showing_;
 
   // Is there a pending system-initiated close?
   bool pending_close_;
 
   DISALLOW_COPY_AND_ASSIGN(BalloonViewImpl);
 };
 
 #endif  // CHROME_BROWSER_UI_GTK_NOTIFICATIONS_BALLOON_VIEW_GTK_H_