Move Singleton and related structs to namespace base

chrome/browser/ui/prefs/prefs_tab_helper.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/ui/prefs/prefs_tab_helper.h"
 
 #include <set>
 #include <string>
 
 #include "base/memory/singleton.h"
@@ skipping 396 matching lines @@
 };
 
 class PrefWatcherFactory : public BrowserContextKeyedServiceFactory {
  public:
   static PrefWatcher* GetForProfile(Profile* profile) {
     return static_cast<PrefWatcher*>(
         GetInstance()->GetServiceForBrowserContext(profile, true));
   }
 
   static PrefWatcherFactory* GetInstance() {
-    return Singleton<PrefWatcherFactory>::get();
+    return base::Singleton<PrefWatcherFactory>::get();
   }
 
  private:
-  friend struct DefaultSingletonTraits<PrefWatcherFactory>;
+  friend struct base::DefaultSingletonTraits<PrefWatcherFactory>;
 
   PrefWatcherFactory() : BrowserContextKeyedServiceFactory(
       "PrefWatcher",
       BrowserContextDependencyManager::GetInstance()) {
   }
 
   ~PrefWatcherFactory() override {}
 
   // BrowserContextKeyedServiceFactory:
   KeyedService* BuildServiceInstanceFor(
@@ skipping 237 matching lines @@
   }
 }
 
 void PrefsTabHelper::OnWebPrefChanged(const std::string& pref_name) {
 #if !defined(OS_ANDROID)
   OnFontFamilyPrefChanged(pref_name);
 #endif
 
   web_contents_->GetRenderViewHost()->OnWebkitPreferencesChanged();
 }