Omit fast forward and rewind actions when current window is not seekable

Issue: #4001

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=189722812

RELEASENOTES.md

@@ -4,6 +4,8 @@
 
 
 * Match codecs starting with "mp4a" to different Audio MimeTypes
 * Match codecs starting with "mp4a" to different Audio MimeTypes
   ([#3779](https://github.com/google/ExoPlayer/issues/3779)).
   ([#3779](https://github.com/google/ExoPlayer/issues/3779)).
+* MediaSession extension: Omit fast forward and rewind actions when media is not
+  seekable ([#4001](https://github.com/google/ExoPlayer/issues/4001)).
 
 
 ### 2.7.1 ###
 ### 2.7.1 ###
 
 

extensions/mediasession/src/main/java/com/google/android/exoplayer2/ext/mediasession/DefaultPlaybackController.java

@@ -77,11 +77,10 @@ public class DefaultPlaybackController implements MediaSessionConnector.Playback
   public long getSupportedPlaybackActions(Player player) {
   public long getSupportedPlaybackActions(Player player) {
     if (player == null || player.getCurrentTimeline().isEmpty()) {
     if (player == null || player.getCurrentTimeline().isEmpty()) {
       return 0;
       return 0;
+    } else if (!player.isCurrentWindowSeekable()) {
+      return BASE_ACTIONS;
     }
     }
-    long actions = BASE_ACTIONS;
-    if (player.isCurrentWindowSeekable()) {
-      actions |= PlaybackStateCompat.ACTION_SEEK_TO;
-    }
+    long actions = BASE_ACTIONS | PlaybackStateCompat.ACTION_SEEK_TO;
     if (fastForwardIncrementMs > 0) {
     if (fastForwardIncrementMs > 0) {
       actions |= PlaybackStateCompat.ACTION_FAST_FORWARD;
       actions |= PlaybackStateCompat.ACTION_FAST_FORWARD;
     }
     }