Source

File: wp-admin/includes/class-bulk-upgrader-skin.php

public function after( $title = '' ) {
		echo '</p></div>';
		if ( $this->error || ! $this->result ) {
			if ( $this->error ) {
				echo '<div class="error"><p>' . sprintf( $this->upgrader->strings['skin_update_failed_error'], $title, '<strong>' . $this->error . '</strong>' ) . '</p></div>';
			} else {
				echo '<div class="error"><p>' . sprintf( $this->upgrader->strings['skin_update_failed'], $title ) . '</p></div>';
			}

			echo '<script type="text/javascript">jQuery(\'#progress-' . esc_js( $this->upgrader->update_current ) . '\').show();</script>';
		}
		if ( $this->result && ! is_wp_error( $this->result ) ) {
			if ( ! $this->error ) {
				echo '<div class="updated js-update-details" data-update-details="progress-' . esc_attr( $this->upgrader->update_current ) . '">' .
					'<p>' . sprintf( $this->upgrader->strings['skin_update_successful'], $title ) .
					' <button type="button" class="hide-if-no-js button-link js-update-details-toggle" aria-expanded="false">' . __( 'Show details.' ) . '</button>' .
					'</p></div>';
			}

			echo '<script type="text/javascript">jQuery(\'.waiting-' . esc_js( $this->upgrader->update_current ) . '\').hide();</script>';
		}

		$this->reset();
		$this->flush_output();
	}