Setting auth.schemes and auth.server_whitelist doesn't seem to work. If I have a CefRefPtr<CefRequestContext> reqCtx and call reqCtx->CanSetPreference("auth"), I get false as a result. Meaning I can't set the auth prefs.
I don't set the prefs in OnContextInitialized (or did you mean OnContextCreated in the render process?). I set it earlier when calling CefBrowserHost::CreateBrowser; CreateBrowser has an argument where I can pass the modified request context. This works for the proxy preference, by the way.
What happens if I retrieve the "auth" prefs dictionary with GetPreference and modify it? Does CEF/Chromium see the modified dictionary if I don't call SetPreference at all?