Make MediaSession a runtime-enabled feature on Desktop.

content/browser/media/session/media_session_controllers_manager.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_SESSION_MEDIA_SESSION_CONTROLLERS_MANAGER_H_
+#define CONTENT_BROWSER_MEDIA_SESSION_MEDIA_SESSION_CONTROLLERS_MANAGER_H_
+
+#include <map>
+#include <utility>
+
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/time/time.h"
+#include "content/public/browser/web_contents_observer.h" // For MediaPlayerId.
+
+namespace content {
+
+class MediaSessionController;
+class MediaWebContentsObserver;
+class RenderFrameHost;
+
+// MediaSessionControllersManager is a delegate of MediaWebContentsObserver that
+// handles MediaSessionController instances.
+class MediaSessionControllersManager {
+ public:
+  using MediaPlayerId = WebContentsObserver::MediaPlayerId;
+
+  explicit MediaSessionControllersManager(
+      MediaWebContentsObserver* media_web_contents_observer);
+  ~MediaSessionControllersManager();
+
+  // Clear all the MediaSessionController associated with the given
+  // |render_frame_host|.
+  void RenderFrameDeleted(RenderFrameHost* render_frame_host);
+
+  // Called before a player starts playing. It will be added to the media
+  // session and will have a controller associated with it.
+  // Returns whether the player was added to the session and can start playing.
+  bool RequestPlay(const MediaPlayerId& id,
+                   bool has_audio,
+                   bool is_remote,
+                   base::TimeDelta duration);
+
+  // Called when the given player |id| has paused.
+  void OnPause(const MediaPlayerId& id);
+
+  // Called when the given player |id| has ended.
+  void OnEnd(const MediaPlayerId& id);
+
+ private:
+  // Weak pointer because |this| is owned by |media_web_contents_observer_|.
+  MediaWebContentsObserver* const media_web_contents_observer_;
+
+  using ControllersMap =
+      std::map<MediaPlayerId, scoped_ptr<MediaSessionController>>;
+  ControllersMap controllers_map_;
+
+  DISALLOW_COPY_AND_ASSIGN(MediaSessionControllersManager);
+};
+
+}  // namespace content
+
+#endif // CONTENT_BROWSER_MEDIA_SESSION_MEDIA_SESSION_CONTROLLERS_MANAGER_H_