Move Singleton and related structs to namespace base

extensions/browser/app_window/app_window_geometry_cache.h

 // Copyright 2014 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.
 
 #ifndef EXTENSIONS_BROWSER_APP_WINDOW_APP_WINDOW_GEOMETRY_CACHE_H_
 #define EXTENSIONS_BROWSER_APP_WINDOW_APP_WINDOW_GEOMETRY_CACHE_H_
 
 #include <map>
 #include <set>
 #include <string>
@@ skipping 24 matching lines @@
  public:
   class Factory : public BrowserContextKeyedServiceFactory {
    public:
     static AppWindowGeometryCache* GetForContext(
         content::BrowserContext* context,
         bool create);
 
     static Factory* GetInstance();
 
    private:
-    friend struct DefaultSingletonTraits<Factory>;
+    friend struct base::DefaultSingletonTraits<Factory>;
 
     Factory();
     ~Factory() override;
 
     // BrowserContextKeyedServiceFactory
     KeyedService* BuildServiceInstanceFor(
         content::BrowserContext* context) const override;
     bool ServiceIsNULLWhileTesting() const override;
     content::BrowserContext* GetBrowserContextToUse(
         content::BrowserContext* context) const override;
@@ skipping 92 matching lines @@
   // Listen to extension load, unloaded notifications.
   ScopedObserver<ExtensionRegistry, ExtensionRegistryObserver>
       extension_registry_observer_;
 
   base::ObserverList<Observer> observers_;
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_APP_WINDOW_APP_WINDOW_GEOMETRY_CACHE_H_