/usr/share/php/Symfony/Component/DependencyInjection/Loader/ is in php-symfony-dependency-injection 2.7.10-0ubuntu2.
This file is owned by root:root, with mode 0o755.
..
/usr/share/php/Symfony/Component/DependencyInjection/Loader/ClosureLoader.php
/usr/share/php/Symfony/Component/DependencyInjection/Loader/FileLoader.php
/usr/share/php/Symfony/Component/DependencyInjection/Loader/IniFileLoader.php
/usr/share/php/Symfony/Component/DependencyInjection/Loader/PhpFileLoader.php
/usr/share/php/Symfony/Component/DependencyInjection/Loader/XmlFileLoader.php
/usr/share/php/Symfony/Component/DependencyInjection/Loader/YamlFileLoader.php
/usr/share/php/Symfony/Component/DependencyInjection/Loader/schema/
/usr/share/php/Symfony/Component/DependencyInjection/Loader/schema/dic/
/usr/share/php/Symfony/Component/DependencyInjection/Loader/schema/dic/services/
/usr/share/php/Symfony/Component/DependencyInjection/Loader/schema/dic/services/services-1.0.xsd