Attempt four at landing the "histogram.h removed from message_loop.h" patch.

chrome/common/desktop_notifications/active_notification_tracker.cc

 // Copyright (c) 2009 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/common/desktop_notifications/active_notification_tracker.h"
 
 #include "base/message_loop.h"
+#include "base/scoped_ptr.h"
 #include "third_party/WebKit/WebKit/chromium/public/WebNotification.h"
 #include "third_party/WebKit/WebKit/chromium/public/WebNotificationPermissionCallback.h"
 
 using WebKit::WebNotification;
 using WebKit::WebNotificationPermissionCallback;
 
 bool ActiveNotificationTracker::GetId(
     const WebNotification& notification, int& id) {
   ReverseTable::iterator iter = reverse_notification_table_.find(notification);
   if (iter == reverse_notification_table_.end())
@@ skipping 42 matching lines @@
 }
 
 int ActiveNotificationTracker::RegisterPermissionRequest(
     WebNotificationPermissionCallback* callback) {
   return callback_table_.Add(callback);
 }
 
 void ActiveNotificationTracker::OnPermissionRequestComplete(int id) {
   callback_table_.Remove(id);
 }