Make members of Singleton<T> private and only visible to the singleton type.

chrome/browser/chromeos/offline/offline_load_service.cc

 // Copyright (c) 2010 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/offline/offline_load_service.h"
 
+#include "base/lazy_instance.h"
 #include "base/ref_counted.h"
-#include "base/singleton.h"
 #include "chrome/browser/browser_thread.h"
 #include "chrome/browser/tab_contents/navigation_controller.h"
 #include "chrome/browser/tab_contents/tab_contents.h"
 #include "chrome/browser/tab_contents/tab_util.h"
 #include "chrome/common/notification_service.h"
 
 namespace chromeos {
 
 // A utility class that serves a singleton instance of OfflineLoadService.
 // OfflineLoadSerivce itself cannot be a singleton as it implements
 // RefCount interface.
 class OfflineLoadServiceSingleton {
  public:
   chromeos::OfflineLoadService* offline_load_service() {
     return offline_load_service_.get();
   }
 
  private:
-  friend struct DefaultSingletonTraits<OfflineLoadServiceSingleton>;
+  friend struct base::DefaultLazyInstanceTraits<OfflineLoadServiceSingleton>;
   OfflineLoadServiceSingleton()
       : offline_load_service_(new chromeos::OfflineLoadService()) {}
   virtual ~OfflineLoadServiceSingleton() {}
 
   scoped_refptr<chromeos::OfflineLoadService> offline_load_service_;
 
   DISALLOW_COPY_AND_ASSIGN(OfflineLoadServiceSingleton);
 };
 
+static base::LazyInstance<OfflineLoadServiceSingleton>
+    g_offline_load_service_singleton(base::LINKER_INITIALIZED);
+
 // static
 OfflineLoadService* OfflineLoadService::Get() {
-  return Singleton<OfflineLoadServiceSingleton>::get()->offline_load_service();
+  return g_offline_load_service_singleton.Get().offline_load_service();
 }
 
 void OfflineLoadService::Observe(NotificationType type,
                                  const NotificationSource& source,
                                  const NotificationDetails& details) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   if (type.value == NotificationType::TAB_CLOSED) {
     registrar_.Remove(this, NotificationType::TAB_CLOSED, source);
     NavigationController* tab = Source<NavigationController>(source).ptr();
     BrowserThread::PostTask(
@@ skipping 45 matching lines @@
 
 void OfflineLoadService::RegisterNotification(
     NavigationController* navigation_controller) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   registrar_.Add(this, NotificationType::TAB_CLOSED,
                    Source<NavigationController>(
                        navigation_controller));
 }
 
 }  // namespace chromeos