Move Singleton and related structs to namespace base

ui/views/focus/widget_focus_manager.cc

 // Copyright (c) 2011 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/views/focus/widget_focus_manager.h"
 
 #include "base/memory/singleton.h"
 
 namespace views {
 
 // WidgetFocusManager ----------------------------------------------------------
 
 // static
 WidgetFocusManager* WidgetFocusManager::GetInstance() {
-  return Singleton<WidgetFocusManager>::get();
+  return base::Singleton<WidgetFocusManager>::get();
 }
 
 void WidgetFocusManager::AddFocusChangeListener(
     WidgetFocusChangeListener* listener) {
   focus_change_listeners_.AddObserver(listener);
 }
 
 void WidgetFocusManager::RemoveFocusChangeListener(
     WidgetFocusChangeListener* listener) {
   focus_change_listeners_.RemoveObserver(listener);
@@ skipping 14 matching lines @@
 
 AutoNativeNotificationDisabler::AutoNativeNotificationDisabler() {
   WidgetFocusManager::GetInstance()->DisableNotifications();
 }
 
 AutoNativeNotificationDisabler::~AutoNativeNotificationDisabler() {
   WidgetFocusManager::GetInstance()->EnableNotifications();
 }
 
 }  // namespace views