queue/Playlist: rename DeleteSong() to StaleSong()

src/Instance.cxx

@@ -66,7 +66,7 @@ Instance::OnDatabaseSongRemoved(const char *uri)
 		sticker_song_delete(uri, IgnoreError());
 #endif
 
-	partition->DeleteSong(uri);
+	partition->StaleSong(uri);
 }
 
 #endif

src/Partition.hxx

@@ -91,14 +91,10 @@ struct Partition final : QueueListener, PlayerListener, MixerListener {
 		playlist.DeleteRange(pc, start, end);
 	}
 
-#ifdef ENABLE_DATABASE
-
-	void DeleteSong(const char *uri) {
-		playlist.DeleteSong(pc, uri);
+	void StaleSong(const char *uri) {
+		playlist.StaleSong(pc, uri);
 	}
 
-#endif
-
 	void Shuffle(unsigned start, unsigned end) {
 		playlist.Shuffle(pc, start, end);
 	}

src/queue/Playlist.hxx

@@ -237,7 +237,13 @@ public:
 	 */
 	void DeleteRange(PlayerControl &pc, unsigned start, unsigned end);
 
-	void DeleteSong(PlayerControl &pc, const char *uri);
+	/**
+	 * Mark the given song as "stale", i.e. as not being available
+	 * anymore.  This gets called when a song is removed from the
+	 * database.  The method attempts to remove all instances of
+	 * this song from the queue.
+	 */
+	void StaleSong(PlayerControl &pc, const char *uri);
 
 	void Shuffle(PlayerControl &pc, unsigned start, unsigned end);
 

src/queue/PlaylistEdit.cxx

@@ -310,7 +310,7 @@ playlist::DeleteId(PlayerControl &pc, unsigned id)
 }
 
 void
-playlist::DeleteSong(PlayerControl &pc, const char *uri)
+playlist::StaleSong(PlayerControl &pc, const char *uri)
 {
 	for (int i = queue.GetLength() - 1; i >= 0; --i)
 		if (queue.Get(i).IsURI(uri))