Add already used optional sizeDifference parameter to IPropagator

Signed-off-by: Julius Härtl <jus@bitgrid.net>

lib/public/Files/Cache/IPropagator.php

@@ -49,7 +49,8 @@ interface IPropagator {
 	/**
 	 * @param string $internalPath
 	 * @param int $time
+	 * @param int $sizeDifference
 	 * @since 9.0.0
 	 */
-	public function propagateChange($internalPath, $time);
+	public function propagateChange($internalPath, $time, $sizeDifference = 0);
 }