How to obtain the system proxy settings from chrome extension?

[Karim Emara]

I need to make a customized proxy settings for my chrome extension so that traffic to a specific domain goes through a proxy server while all other (user) traffic goes normally with the default system settings. According to the chrome API documentation, the only way is to use pac_script (correct me if I am wrong). Thus, the code will be something like this:

var config = {
mode: "pac_script",
pacScript: {
data: "function FindProxyForURL(url, host) {\n" +
" if (dnsDomainIs(host, 'mydomain.com') )\n" +
" return 'SOCKS5 10.0.0.1:1234';\n" +
" return 'DIRECT';\n" +
"}"
}};
chrome.proxy.settings.set({value: config, scope: 'regular'});
However, pac_script does not have the option to route traffic using system proxy settings (only 'DIRECT' which means it will skip the system settings). I thought to obtain the system proxy settings using chrome.proxy.settings.get, but this function returns an object where mode = system with no useful information.

Does anyone know how to obtain the system proxy settings from extension? Or has suggestions to handle the original problem?