Move Singleton and related structs to namespace base

chrome/browser/ui/app_list/app_list_service_disabled.cc

Index: chrome/browser/ui/app_list/app_list_service_disabled.cc
diff --git a/chrome/browser/ui/app_list/app_list_service_disabled.cc b/chrome/browser/ui/app_list/app_list_service_disabled.cc
index 25293ae6926fc877222a345f9989880bbe7bfb07..cdb4f4ed6b55ae47a9ebf469dc7138d8ee1fb25e 100644
--- a/chrome/browser/ui/app_list/app_list_service_disabled.cc
+++ b/chrome/browser/ui/app_list/app_list_service_disabled.cc
@@ -11,12 +11,13 @@ namespace {
 class AppListServiceDisabled : public AppListService {
  public:
   static AppListServiceDisabled* GetInstance() {
-    return Singleton<AppListServiceDisabled,
-                     LeakySingletonTraits<AppListServiceDisabled> >::get();
+    return base::Singleton<
+        AppListServiceDisabled,
+        base::LeakySingletonTraits<AppListServiceDisabled>>::get();
   }
 
  private:
-  friend struct DefaultSingletonTraits<AppListServiceDisabled>;
+  friend struct base::DefaultSingletonTraits<AppListServiceDisabled>;
 
   AppListServiceDisabled() {}