How to close the application on the chrome custom close tab

Question

I want the application to close when the user closes the user tab.

I experimented with:

public interface ConnectionCallback {
        /**
         * Called when the service is connected.
         */
        void onCustomTabsConnected();

        /**
         * Called when the service is disconnected.
         */
        void onCustomTabsDisconnected();
    }

but does not work.

ps new for android / java