Add more missing closing namespace comments.

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

 // Copyright 2015 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 "core/html/AutoplayExperimentHelper.h"
 
 #include "core/dom/Document.h"
 #include "core/frame/FrameView.h"
 #include "core/frame/Settings.h"
 #include "core/html/HTMLMediaElement.h"
@@ skipping 345 matching lines @@
     if (mode.contains("-ifmuted"))
         value |= IfMuted;
     if (mode.contains("-ifmobile"))
         value |= IfMobile;
     if (mode.contains("-playmuted"))
         value |= PlayMuted;
 
     return value;
 }
 
-}
+} // namespace blink