db/DatabaseListener: add method OnDatabaseSongRemoved()

Decouples db/update/Remove.cpp from global variables.

src/Instance.cxx

@@ -22,9 +22,15 @@
 #include "Partition.hxx"
 #include "Idle.hxx"
 #include "Stats.hxx"
-#include "db/DatabaseError.hxx"
 
 #ifdef ENABLE_DATABASE
+#include "db/DatabaseError.hxx"
+#include "db/LightSong.hxx"
+
+#ifdef ENABLE_SQLITE
+#include "sticker/StickerDatabase.hxx"
+#include "sticker/SongSticker.hxx"
+#endif
 
 Database *
 Instance::GetDatabase(Error &error)
@@ -34,12 +40,6 @@ Instance::GetDatabase(Error &error)
 	return database;
 }
 
-void
-Instance::DeleteSong(const char *uri)
-{
-	partition->DeleteSong(uri);
-}
-
 #endif
 
 void
@@ -68,6 +68,21 @@ Instance::OnDatabaseModified()
 	idle_add(IDLE_DATABASE);
 }
 
+void
+Instance::OnDatabaseSongRemoved(const LightSong &song)
+{
+	assert(database != nullptr);
+
+#ifdef ENABLE_SQLITE
+	/* if the song has a sticker, remove it */
+	if (sticker_enabled())
+		sticker_song_delete(song);
+#endif
+
+	const auto uri = song.GetURI();
+	partition->DeleteSong(uri.c_str());
+}
+
 #endif
 
 #ifdef ENABLE_NEIGHBOR_PLUGINS