Move Singleton and related structs to namespace base

ios/chrome/browser/autocomplete/autocomplete_classifier_factory.cc

 // Copyright 2015 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 "ios/chrome/browser/autocomplete/autocomplete_classifier_factory.h"
 
 #include "base/memory/singleton.h"
 #include "components/keyed_service/ios/browser_state_dependency_manager.h"
 #include "components/omnibox/browser/autocomplete_classifier.h"
 #include "components/omnibox/browser/autocomplete_controller.h"
@@ skipping 23 matching lines @@
 
 // static
 AutocompleteClassifier* AutocompleteClassifierFactory::GetForBrowserState(
     ios::ChromeBrowserState* browser_state) {
   return static_cast<AutocompleteClassifier*>(
       GetInstance()->GetServiceForBrowserState(browser_state, true));
 }
 
 // static
 AutocompleteClassifierFactory* AutocompleteClassifierFactory::GetInstance() {
-  return Singleton<AutocompleteClassifierFactory>::get();
+  return base::Singleton<AutocompleteClassifierFactory>::get();
 }
 
 // static
 BrowserStateKeyedServiceFactory::TestingFactoryFunction
 AutocompleteClassifierFactory::GetDefaultFactory() {
   return &BuildAutocompleteClassifier;
 }
 
 AutocompleteClassifierFactory::AutocompleteClassifierFactory()
     : BrowserStateKeyedServiceFactory(
@@ skipping 14 matching lines @@
 web::BrowserState* AutocompleteClassifierFactory::GetBrowserStateToUse(
     web::BrowserState* context) const {
   return GetBrowserStateRedirectedInIncognito(context);
 }
 
 bool AutocompleteClassifierFactory::ServiceIsNULLWhileTesting() const {
   return true;
 }
 
 }  // namespace ios