Move Singleton and related structs to namespace base

chrome/browser/favicon/large_icon_service_factory.h

Index: chrome/browser/favicon/large_icon_service_factory.h
diff --git a/chrome/browser/favicon/large_icon_service_factory.h b/chrome/browser/favicon/large_icon_service_factory.h
index 46a9e5bb6f4756c7be0ca917b92eca1f58cf3702..db5a1672bbcd21e910f063e741786557f440a201 100644
--- a/chrome/browser/favicon/large_icon_service_factory.h
+++ b/chrome/browser/favicon/large_icon_service_factory.h
@@ -7,7 +7,9 @@
 
 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
 
+namespace base {
 template <typename T> struct DefaultSingletonTraits;
+}
 
 namespace content {
 class BrowserContext;
@@ -27,7 +29,7 @@ class LargeIconServiceFactory : public BrowserContextKeyedServiceFactory {
   static LargeIconServiceFactory* GetInstance();
 
  private:
-  friend struct DefaultSingletonTraits<LargeIconServiceFactory>;
+  friend struct base::DefaultSingletonTraits<LargeIconServiceFactory>;
 
   LargeIconServiceFactory();
   ~LargeIconServiceFactory() override;