Add more missing closing namespace comments.

third_party/WebKit/Source/modules/mediasession/HTMLMediaElementMediaSession.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 "modules/mediasession/HTMLMediaElementMediaSession.h"
 
 #include "core/dom/ExceptionCode.h"
 
 namespace blink {
 
@@ skipping 34 matching lines @@
 {
     return static_cast<HTMLMediaElementMediaSession*>(WillBeHeapSupplement<HTMLMediaElement>::from(element, supplementName()));
 }
 
 DEFINE_TRACE(HTMLMediaElementMediaSession)
 {
     visitor->trace(m_session);
     WillBeHeapSupplement<HTMLMediaElement>::trace(visitor);
 }
 
-}
-
+} // namespace blink