An update to @rleelr:
It's possible to view proxy settings in Google Chrome:
chrome://net-internals/#http2
Then select
View live HTTP/2 sessions
Then select one of the live sessions (you need to have some tabs open). There you find:
[...]
t=504112 [st= 0] +HTTP2_SESSION [dt=?]
--> host = "play.google.com:443"
--> proxy = "PROXY www.xxx.yyy.zzz:8080"
[...]
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