Session timeout Chrome JSXC

I have an Openfire server v 4.7.5. I´m using LDAP authentication and Spark client. All is working fine.
Now, I want to add the option to use the web client based on JSXC Openfire plugin. Again, I can install and configure and works fine in Mozilla Firefox.

But when I use Google Chrome to access the web chat the session is autoclosed in 3min of inactivity. I set the Idle Connection Policy to “no disconnect” and send “XMPP ping”.
As I said, with Firefox I don´t have any problem. The client session keeps alive, but Chrome closes it.

I tried with Chrome Performance Settings, adding the plugin url to “Keep Active site”. But does not work.

Any idea?