Move Singleton and related structs to namespace base

components/app_modal/app_modal_dialog_queue.cc

 // Copyright (c) 2012 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 "components/app_modal/app_modal_dialog_queue.h"
 
 #include "base/memory/singleton.h"
 #include "components/app_modal/app_modal_dialog.h"
 
 namespace app_modal {
 
 // static
 AppModalDialogQueue* AppModalDialogQueue::GetInstance() {
-  return Singleton<AppModalDialogQueue>::get();
+  return base::Singleton<AppModalDialogQueue>::get();
 }
 
 void AppModalDialogQueue::AddDialog(AppModalDialog* dialog) {
   if (!active_dialog_) {
     ShowModalDialog(dialog);
     return;
   }
   app_modal_dialog_queue_.push_back(dialog);
 }
 
@@ skipping 46 matching lines @@
     AppModalDialog* dialog = app_modal_dialog_queue_.front();
     app_modal_dialog_queue_.pop_front();
     if (dialog->IsValid())
       return dialog;
     delete dialog;
   }
   return NULL;
 }
 
 }  // namespace app_modal