iwyu: Use callback_old.h where appropriate, part 2.

chrome/browser/notifications/balloon_collection.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.
 
 // Handles the visible notification (or balloons).
 
 #ifndef CHROME_BROWSER_NOTIFICATIONS_BALLOON_COLLECTION_H_
 #define CHROME_BROWSER_NOTIFICATIONS_BALLOON_COLLECTION_H_
 #pragma once
 
 #include <deque>
 #include <string>
 
-#include "base/callback.h"
+#include "base/callback_old.h"
 #include "base/memory/scoped_ptr.h"
 
 class Balloon;
 class GURL;
 class Notification;
 class Profile;
 
 namespace gfx {
 class Size;
 }  // namespace gfx
@@ skipping 75 matching lines @@
  protected:
   // Non-owned pointer to an object listening for space changes.
   BalloonSpaceChangeListener* space_change_listener_;
 
   // For use only with testing. This callback is invoked when a balloon
   // is added or removed from the collection.
   scoped_ptr<Callback0::Type> on_collection_changed_callback_;
 };
 
 #endif  // CHROME_BROWSER_NOTIFICATIONS_BALLOON_COLLECTION_H_