There is nothing an extension can do by itself to do this - it would introduce some pretty huge security holes if there was. Ideally, if you control the back end you get a certificate through free providers like
Lets Encrypt. If you
don't have the ability to configure the host, another option would be to set up a proxy that you extension uses, that doesn't have an invalid certificate. Finally, individual users are able to ignore certificate errors by launching Chrome with the `--ignore-certificate-errors` flag. This is
really not recommended unless you are testing very specific things, as it means you are 100% unprotected against any malicious SSL certs.