Computer Configuration > Administrative Templates > Google Chrome > HTTP authentication
Both
HKLM\Software\Policies\Google\Chrome
Setting the policy to Enabled or leaving it unset will allow Basic authentication challenges received over non-secure HTTP. Setting the policy to Disabled forbids non-secure HTTP requests from using the Basic authentication scheme; only secure HTTPS is allowed. This policy setting is ignored (and Basic is always forbidden) if the AuthSchemes policy is set and does not include Basic.