Add more missing closing namespace comments.

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

 /*
  * Copyright (C) 2008 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 133 matching lines @@
 
         KeyboardEvent* keyboardEvent = toKeyboardEvent(event);
         if (keyboardEvent->keyIdentifier() == "U+0020" || keyboardEvent->keyCode() == VKEY_MEDIA_PLAY_PAUSE) {
             // space or media key (play/pause)
             video->togglePlayState();
             event->setDefaultHandled();
         }
     }
 }
 
-}
+} // namespace blink