Add more missing closing namespace comments.

third_party/WebKit/Source/core/html/MediaDocument.h

 /*
  * Copyright (C) 2008,2009 Apple Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 29 matching lines @@
 private:
     MediaDocument(const DocumentInit&);
 
     PassRefPtrWillBeRawPtr<DocumentParser> createParser() override;
 
     void defaultEventHandler(Event*) override;
 
     String debugName() const override { return "MediaDocument"; }
 };
 
-}
+} // namespace blink
 
 #endif