Add more missing closing namespace comments.

third_party/WebKit/Source/platform/PopupMenu.h

 /*
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 22 matching lines @@
 class PopupMenu : public RefCountedWillBeGarbageCollectedFinalized<PopupMenu> {
 public:
     virtual ~PopupMenu() { }
     DEFINE_INLINE_VIRTUAL_TRACE() { }
     virtual void show(const FloatQuad& controlPosition, const IntSize& controlSize, int index) = 0;
     virtual void hide() = 0;
     virtual void updateFromElement() = 0;
     virtual void disconnectClient() = 0;
 };
 
-}
+} // namespace blink
 
 #endif // PopupMenu_h