/usr/share/php/ is in php-dropbox 1.0.0-4ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/php/.registry/
/usr/share/php/.registry/.channel.pear.dropbox-php.com/
/usr/share/php/.registry/.channel.pear.dropbox-php.com/dropbox.reg
/usr/share/php/Dropbox/
/usr/share/php/Dropbox/Exception.php
/usr/share/php/Dropbox/OAuth.php
/usr/share/php/Dropbox/API.php
/usr/share/php/Dropbox/autoload.php
/usr/share/php/Dropbox/Exception/
/usr/share/php/Dropbox/Exception/RequestToken.php
/usr/share/php/Dropbox/Exception/Forbidden.php
/usr/share/php/Dropbox/Exception/NotFound.php
/usr/share/php/Dropbox/Exception/OverQuota.php
/usr/share/php/Dropbox/OAuth/
/usr/share/php/Dropbox/OAuth/Zend.php
/usr/share/php/Dropbox/OAuth/PEAR.php
/usr/share/php/Dropbox/OAuth/PHP.php
/usr/share/php/Dropbox/OAuth/Curl.php
/usr/share/php/Dropbox/OAuth/Consumer/
/usr/share/php/Dropbox/OAuth/Consumer/Dropbox.php
/usr/share/php/Dropbox/OAuth/Wordpress.php