function ob_callback(&$buffer) { if ($this->_config->get_boolean('newrelic.include_rum')) { if (($this->_config->get_boolean('browsercache.html.compression') || $this->_config->get_string('pgcache.engine') == 'file_generic') && !$this->_should_disable_auto_rum()) { $buffer = preg_replace('~<head(\\s+[^<>]+)*>~Ui', '\\0' . NewRelicWrapper::get_browser_timing_header(), $buffer, 1); $buffer = preg_replace('~<\\/body>~', NewRelicWrapper::get_browser_timing_footer() . '\\0', $buffer, 1); } } return $buffer; }