/etc/xul-ext/foxyproxy-standard.js is in xul-ext-foxyproxy-standard 3.4-1.1~deb7u1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 | // Place your preferences for xul-ext-foxyproxy-standard in this file.
// You can override here the preferences specified in
// /usr/share/xul-ext/foxyproxy-standard/defaults/preferences/prefs.js
|