Move Singleton and related structs to namespace base

ui/chromeos/ime/input_method_menu_manager.cc

 // 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.
 
 #include "ui/chromeos/ime/input_method_menu_manager.h"
 
 #include "base/logging.h"
 #include "base/memory/singleton.h"
 
 namespace ui {
@@ skipping 32 matching lines @@
   for (size_t i = 0; i < menu_list_.size(); ++i) {
     if (menu_list_[i].key == key) {
       return true;
     }
   }
   return false;
 }
 
 // static
 InputMethodMenuManager* InputMethodMenuManager::GetInstance() {
-  return Singleton<InputMethodMenuManager>::get();
+  return base::Singleton<InputMethodMenuManager>::get();
 }
 
 }  // namespace ime
 }  // namespace ui