Make MediaSession a runtime-enabled feature on Desktop.

content/browser/media/session/media_session_controller.h

 // Copyright 2016 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_BROWSER_MEDIA_ANDROID_MEDIA_SESSION_CONTROLLER_H_
-#define CONTENT_BROWSER_MEDIA_ANDROID_MEDIA_SESSION_CONTROLLER_H_
+#ifndef CONTENT_BROWSER_MEDIA_SESSION_MEDIA_SESSION_CONTROLLER_H_
+#define CONTENT_BROWSER_MEDIA_SESSION_MEDIA_SESSION_CONTROLLER_H_
 
+#include "base/compiler_specific.h"
 #include "base/time/time.h"
-#include "content/browser/media/android/media_session_observer.h"
+#include "content/browser/media/session/media_session_observer.h"
 #include "content/common/content_export.h"
 #include "content/public/browser/web_contents_observer.h"
 
 namespace content {
 
 class MediaSession;
 class MediaWebContentsObserver;
 
 // Helper class for controlling a single player's MediaSession instance.  Sends
 // browser side MediaSession commands back to a player hosted in the renderer
 // process.
-class CONTENT_EXPORT MediaSessionController : public MediaSessionObserver {
+class CONTENT_EXPORT MediaSessionController :
+    NON_EXPORTED_BASE(public MediaSessionObserver) {
  public:
   MediaSessionController(const WebContentsObserver::MediaPlayerId& id,
                          MediaWebContentsObserver* media_web_contents_observer);
   ~MediaSessionController() override;
 
   // Minimum duration of content for a MediaSession instance to be created.
   enum { kMinimumDurationForContentSecs = 5 };
 
   // Clients must call this after construction and destroy the controller if it
   // returns false.  May be called more than once; does nothing if none of the
@@ skipping 27 matching lines @@
   MediaSession* const media_session_;
 
   int player_id_ = 0;
   bool has_session_ = false;
 
   DISALLOW_COPY_AND_ASSIGN(MediaSessionController);
 };
 
 }  // namespace content
 
-#endif  // CONTENT_BROWSER_MEDIA_ANDROID_MEDIA_SESSION_CONTROLLER_H_
+#endif  // CONTENT_BROWSER_MEDIA_SESSION_MEDIA_SESSION_CONTROLLER_H_