Make sure WindowObservers are removed from window before destruction

chrome/browser/chromeos/extensions/wallpaper_private_api.cc

 // Copyright (c) 2013 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/chromeos/extensions/wallpaper_private_api.h"
 
 #include <vector>
 
 #include "ash/ash_switches.h"
 #include "ash/desktop_background/desktop_background_controller.h"
@@ skipping 204 matching lines @@
        iter != user_id_hash_window_list_map_.end();
        ++iter) {
     if (iter->second.find(window) != iter->second.end())
       return;
   }
   // Remove observer if |window| is not observed by any users.
   window->RemoveObserver(this);
 }
 
 void WindowStateManager::OnWindowDestroyed(aura::Window* window) {
-  window->RemoveObserver(this);
-
   for (UserIDHashWindowListMap::iterator iter =
            user_id_hash_window_list_map_.begin();
        iter != user_id_hash_window_list_map_.end();
        ++iter) {
     iter->second.erase(window);
   }
 }
 
 }  // namespace
 
@@ skipping 605 matching lines @@
                  this, file_list));
 }
 
 void WallpaperPrivateGetOfflineWallpaperListFunction::OnComplete(
     const std::vector<std::string>& file_list) {
   ListValue* results = new ListValue();
   results->AppendStrings(file_list);
   SetResult(results);
   SendResponse(true);
 }