Fix when playback is started from MediaSessionCompat.Callback (#6295)

In that case:
- The service does not go through onStartCommand, so it does not go to foreground state.
- The media session is already destroyed.

Now, create a new media session and definitely start foreground service when something is playing.

core/src/main/java/de/danoeh/antennapod/core/service/playback/PlaybackService.java

@@ -220,6 +220,24 @@ public class PlaybackService extends MediaBrowserServiceCompat {
         PreferenceManager.getDefaultSharedPreferences(this)
                 .registerOnSharedPreferenceChangeListener(prefListener);
 
+        recreateMediaSessionIfNeeded();
+        castStateListener = new CastStateListener(this) {
+            @Override
+            public void onSessionStartedOrEnded() {
+                recreateMediaPlayer();
+            }
+        };
+        EventBus.getDefault().post(new PlaybackServiceEvent(PlaybackServiceEvent.Action.SERVICE_STARTED));
+    }
+
+    void recreateMediaSessionIfNeeded() {
+        if (mediaSession != null) {
+            // Media session was not destroyed, so we can re-use it.
+            if (!mediaSession.isActive()) {
+                mediaSession.setActive(true);
+            }
+            return;
+        }
         ComponentName eventReceiver = new ComponentName(getApplicationContext(), MediaButtonReceiver.class);
         Intent mediaButtonIntent = new Intent(Intent.ACTION_MEDIA_BUTTON);
         mediaButtonIntent.setComponent(eventReceiver);
@@ -243,13 +261,6 @@ public class PlaybackService extends MediaBrowserServiceCompat {
 
         recreateMediaPlayer();
         mediaSession.setActive(true);
-        castStateListener = new CastStateListener(this) {
-            @Override
-            public void onSessionStartedOrEnded() {
-                recreateMediaPlayer();
-            }
-        };
-        EventBus.getDefault().post(new PlaybackServiceEvent(PlaybackServiceEvent.Action.SERVICE_STARTED));
     }
 
     void recreateMediaPlayer() {
@@ -290,6 +301,7 @@ public class PlaybackService extends MediaBrowserServiceCompat {
         PreferenceManager.getDefaultSharedPreferences(this).unregisterOnSharedPreferenceChangeListener(prefListener);
         if (mediaSession != null) {
             mediaSession.release();
+            mediaSession = null;
         }
         unregisterReceiver(autoStateUpdated);
         unregisterReceiver(headsetDisconnected);
@@ -702,6 +714,8 @@ public class PlaybackService extends MediaBrowserServiceCompat {
 
         mediaPlayer.playMediaObject(playable, stream, true, true);
         stateManager.validStartCommandWasReceived();
+        stateManager.startForeground(R.id.notification_playing, notificationBuilder.build());
+        recreateMediaSessionIfNeeded();
         updateNotificationAndMediaSession(playable);
         addPlayableToQueue(playable);
     }
@@ -774,9 +788,11 @@ public class PlaybackService extends MediaBrowserServiceCompat {
                 case PLAYING:
                     PlaybackPreferences.writePlayerStatus(mediaPlayer.getPlayerStatus());
                     saveCurrentPosition(true, null, Playable.INVALID_TIME);
+                    recreateMediaSessionIfNeeded();
                     updateNotificationAndMediaSession(newInfo.playable);
                     setupPositionObserver();
                     stateManager.validStartCommandWasReceived();
+                    stateManager.startForeground(R.id.notification_playing, notificationBuilder.build());
                     // set sleep timer if auto-enabled
                     if (newInfo.oldPlayerStatus != null && newInfo.oldPlayerStatus != PlayerStatus.SEEKING
                             && SleepTimerPreferences.autoEnable() && !sleepTimerActive()) {