Ensure both PanelBrowserWindowGtk and BalloonCollectionImpl call RemoveObserver.

chrome/browser/notifications/balloon_collection_impl.cc

 // Copyright (c) 2012 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.
 
 #include "chrome/browser/notifications/balloon_collection_impl.h"
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/stl_util.h"
 #include "chrome/browser/notifications/balloon.h"
@@ skipping 38 matching lines @@
                  content::NotificationService::AllSources());
   registrar_.Add(this, chrome::NOTIFICATION_PANEL_CLOSED,
                  content::NotificationService::AllSources());
   registrar_.Add(this, chrome::NOTIFICATION_PANEL_CHANGED_BOUNDS,
                  content::NotificationService::AllSources());
 
   SetPositionPreference(BalloonCollection::DEFAULT_POSITION);
 }
 
 BalloonCollectionImpl::~BalloonCollectionImpl() {
+#if USE_OFFSETS
+  RemoveMessageLoopObserver();
+#endif
 }
 
 void BalloonCollectionImpl::AddImpl(const Notification& notification,
                                     Profile* profile,
                                     bool add_to_front) {
   Balloon* new_balloon = MakeBalloon(notification, profile);
   // The +1 on width is necessary because width is fixed on notifications,
   // so since we always have the max size, we would always hit the scrollbar
   // condition.  We are only interested in comparing height to maximum.
   new_balloon->set_min_scrollbar_size(gfx::Size(1 + layout_.max_balloon_width(),
@@ skipping 417 matching lines @@
   gfx::Rect new_work_area = gfx::Screen::GetPrimaryMonitorWorkArea();
 #endif
   if (!work_area_.Equals(new_work_area)) {
     work_area_.SetRect(new_work_area.x(), new_work_area.y(),
                        new_work_area.width(), new_work_area.height());
     changed = true;
   }
 
   return changed;
 }