Called on the IO thread when a resource load is redirected. The |browser| and |frame| values represent the source of the request, and may be NULL for requests originating from service workers or cef_urlrequest_t. The |request| parameter will contain the old URL and other request-related information. The |response| parameter will contain the response that resulted in the redirect. The |new_url| parameter will contain the new URL and can be changed if desired. The |request| and |response| objects cannot be modified in this callback.