Move Singleton and related structs to namespace base

chrome/browser/ui/app_list/search/history_factory.cc

 // Copyright 2013 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/app_list/search/history_factory.h"
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/singleton.h"
 #include "components/keyed_service/content/browser_context_dependency_manager.h"
 #include "content/public/browser/browser_context.h"
 #include "content/public/browser/browser_thread.h"
 #include "ui/app_list/search/dictionary_data_store.h"
 #include "ui/app_list/search/history.h"
 #include "ui/app_list/search/history_data_store.h"
 
 namespace app_list {
 
 // static
 HistoryFactory* HistoryFactory::GetInstance() {
-  return Singleton<HistoryFactory>::get();
+  return base::Singleton<HistoryFactory>::get();
 }
 
 // static
 History* HistoryFactory::GetForBrowserContext(
     content::BrowserContext* context) {
   return static_cast<History*>(
       GetInstance()->GetServiceForBrowserContext(context, true));
 }
 
 HistoryFactory::HistoryFactory()
@@ skipping 10 matching lines @@
       context->GetPath().AppendASCII(kStoreDataFileName);
   scoped_refptr<DictionaryDataStore> dictionary_data_store(
       new DictionaryDataStore(data_file,
                               content::BrowserThread::GetBlockingPool()));
   scoped_refptr<HistoryDataStore> history_data_store(
       new HistoryDataStore(dictionary_data_store));
   return new History(history_data_store);
 }
 
 }  // namespace app_list