Remove #pragma once from content

content/public/browser/media_observer.h

 // Copyright (c) 2012 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.
 
 #ifndef CONTENT_PUBLIC_BROWSER_MEDIA_OBSERVER_H_
 #define CONTENT_PUBLIC_BROWSER_MEDIA_OBSERVER_H_
-#pragma once
 
 #include "content/public/common/media_stream_request.h"
 
 namespace media {
 struct MediaLogEvent;
 }
 
 namespace content {
 
 // An embedder may implement MediaObserver and return it from
@@ skipping 32 matching lines @@
       int render_view_id,
       const content::MediaStreamDevices& devices) = 0;
 
  protected:
   virtual ~MediaObserver() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_MEDIA_OBSERVER_H_