Chrome Version       : 69.0.3497.35 (Build oficial) dev (64 bits)
URLs (if applicable) : https://chrome.google.com/webstore/detail/secure-shell-app/pnhechapfaindjhompbnflcldabbghjo?hl=es-419
Other browsers tested: None as it's a Chrome APP

What steps will reproduce the problem?
(1) On the ssh server, start a web server on the 8080 port on a host
(2) On the client, start the SSH App and on 'ssh arguments' write '-L 8080:*8080 -g'
(3) Open a new tab and go to localhost:8080
(4) On other device on the same network, go to <ssh_client_address>:8080

What is the expected result?
Both should work, if the -g flag is removed localhost:8080 can be accessed.

What happens instead?
The local device ('localhost') and the device mentioned in the 4th point says that the connection is refused, so the device is not listening on the external ip address.

Please provide any additional information below. Attach a screenshot if
possible.

If the -v option is passed, you can see that the NaCl client supports the -g flag, but Chrome doesn't let the extension bind an external port. The web server for chrome app has in it's manifest an example of how to request the permission to bind any arbitrary port.
Maybe only a change in the manifest is needed.