change notification bar icon for popup and background player

app/src/main/java/org/schabi/newpipe/player/BackgroundPlayer.java

@@ -177,7 +177,7 @@ public final class BackgroundPlayer extends Service {
 
         NotificationCompat.Builder builder = new NotificationCompat.Builder(this, getString(R.string.notification_channel_id))
                 .setOngoing(true)
-                .setSmallIcon(R.drawable.ic_play_circle_filled_white_24dp)
+                .setSmallIcon(R.drawable.ic_newpipe_triangle_white)
                 .setVisibility(NotificationCompat.VISIBILITY_PUBLIC)
                 .setCustomContentView(notRemoteView)
                 .setCustomBigContentView(bigNotRemoteView);

app/src/main/java/org/schabi/newpipe/player/PopupVideoPlayer.java

@@ -275,7 +275,7 @@ public final class PopupVideoPlayer extends Service {
 
         return new NotificationCompat.Builder(this, getString(R.string.notification_channel_id))
                 .setOngoing(true)
-                .setSmallIcon(R.drawable.ic_play_arrow_white)
+                .setSmallIcon(R.drawable.ic_newpipe_triangle_white)
                 .setVisibility(NotificationCompat.VISIBILITY_PUBLIC)
                 .setContent(notRemoteView);
     }