Link MediaSessionTabHelper with native MediaSession [CL is going to be split]

content/browser/media/session/media_session.h

 // 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.
 
 #ifndef CONTENT_BROWSER_MEDIA_SESSION_MEDIA_SESSION_H_
 #define CONTENT_BROWSER_MEDIA_SESSION_MEDIA_SESSION_H_
 
 #include <stddef.h>
 
+#include "base/android/scoped_java_ref.h"
 #include "base/callback_list.h"
 #include "base/id_map.h"
 #include "base/macros.h"
+#include "base/observer_list.h"
 #include "base/optional.h"
 #include "content/browser/media/session/audio_focus_manager.h"
 #include "content/browser/media/session/media_session_uma_helper.h"
 #include "content/common/content_export.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "content/public/browser/web_contents_user_data.h"
 #include "content/public/common/media_metadata.h"
 
 class MediaSessionBrowserTest;
 
 namespace media {
 enum class MediaContentType;
 }  // namespace media
 
 namespace content {
 
 class AudioFocusDelegate;
 class AudioFocusManagerTest;
 class MediaSessionPlayerObserver;
+class MediaSessionObserver;
 class MediaSessionStateObserver;
 class MediaSessionVisibilityBrowserTest;
 
+#if defined(OS_ANDROID)
+class MediaSessionAndroid;
+#endif  // defined(OS_ANDROID)
+
 // MediaSession manages the media session and audio focus for a given
 // WebContents. It is requesting the audio focus, pausing when requested by the
 // system and dropping it on demand.
 // The audio focus can be of two types: Transient or Content. A Transient audio
 // focus will allow other players to duck instead of pausing and will be
 // declared as temporary to the system. A Content audio focus will not be
 // declared as temporary and will not allow other players to duck. If a given
 // WebContents can only have one audio focus at a time, it will be Content in
 // case of Transient and Content audio focus are both requested.
 // TODO(thakis,mlamouri): MediaSession isn't CONTENT_EXPORT'd because it creates
@@ skipping 19 matching lines @@
     SUSPENDED,
     INACTIVE
   };
 
   // Returns the MediaSession associated to this WebContents. Creates one if
   // none is currently available.
   CONTENT_EXPORT static MediaSession* Get(WebContents* web_contents);
 
   ~MediaSession() override;
 
+#if defined(OS_ANDROID)
+  static MediaSession* FromJavaMediaSession(
+      const base::android::JavaRef<jobject>& j_media_session);
+  MediaSessionAndroid* session_android() const {
+    return session_android_.get();
+  }
+#endif  // defined(OS_ANDROID)
+
+  // Add and remove an observer for MediaSession messages. Clients must remove
+  // the observer before they go away, or pass the observer ownership to
+  // MediaSession via PassObserverOwnership (then the observer will go away when
+  // the session is destroyed. AddObserver() can only be called in
+  // MediaSessionObserver constructor, and cannot be called explicitly.
+  void AddObserver(MediaSessionObserver* observer);
+  void RemoveObserver(MediaSessionObserver* observer);
+
   void SetMetadata(const base::Optional<MediaMetadata>& metadata);
   const base::Optional<MediaMetadata>& metadata() const { return metadata_; }
 
   // Adds the given player to the current media session. Returns whether the
   // player was successfully added. If it returns false, AddPlayer() should be
   // called again later.
   CONTENT_EXPORT bool AddPlayer(MediaSessionPlayerObserver* observer,
                                 int player_id,
                                 media::MediaContentType media_content_type);
 
@@ skipping 146 matching lines @@
   MediaSessionUmaHelper uma_helper_;
 
   // The ducking state of this media session. The initial value is |false|, and
   // is set to |true| after StartDucking(), and will be set to |false| after
   // StopDucking().
   bool is_ducking_;
 
   base::Optional<MediaMetadata> metadata_;
   base::CallbackList<void(State)> media_session_state_listeners_;
 
+  // The list of observers notified when the MediaSession changes.
+  base::ObserverList<MediaSessionObserver> observers_;
+
+#if defined(OS_ANDROID)
+  std::unique_ptr<MediaSessionAndroid> session_android_;
+#endif  // defined(OS_ANDROID)
+
   DISALLOW_COPY_AND_ASSIGN(MediaSession);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_MEDIA_SESSION_MEDIA_SESSION_H_