Move Singleton and related structs to namespace base

ui/base/x/x11_foreign_window_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/base/x/x11_foreign_window_manager.h"
 
 #include <X11/Xlib.h>
 
 #include "base/compiler_specific.h"
 #include "base/memory/singleton.h"
 
 namespace ui {
 
 // static
 XForeignWindowManager* XForeignWindowManager::GetInstance() {
-  return Singleton<XForeignWindowManager>::get();
+  return base::Singleton<XForeignWindowManager>::get();
 }
 
 int XForeignWindowManager::RequestEvents(XID xid, long event_mask) {
   request_map_[xid].push_back(Request(next_request_id_, event_mask));
   UpdateSelectedEvents(xid);
   return next_request_id_++;
 }
 
 void XForeignWindowManager::CancelRequest(int request_id) {
   for (std::map<XID, RequestVector>::iterator map_it = request_map_.begin();
@@ skipping 37 matching lines @@
 
 XForeignWindowManager::Request::Request(int request_id, long event_mask)
     : request_id(request_id),
       event_mask(event_mask) {
 }
 
 XForeignWindowManager::Request::~Request() {
 }
 
 }  // namespace ui