Piwik\AssetManager\UIAssetMerger\StylesheetUIAssetMerger::rewriteCssImagePaths PHP Method

    private function rewriteCssImagePaths($content, $pathsRewriter)
    {
        $content = preg_replace_callback("/(url\\(['\"]?)([^'\")]*)/", $pathsRewriter, $content);
        return $content;
    }