Add xmpp_login extended permission to facebook sdk
<p>I'm using the following code to allow the user to login and authenticate with facebook, which gives me the access_token. How do I add the xmpp_login extended permission to my request for my access_token.</p>

<p>On <a href="https://developers.facebook.com/docs/chat/#platauth" rel="nofollow">this Facebook</a> page it says "In order to connect using this mechanism, the user must first log in to your application and grant the xmpp_login extended permission. Follow the client side flow to get a valid access_token for the user with the xmpp_login extended permission."</p>

<pre><code>    Settings.addLoggingBehavior(LoggingBehavior.INCLUDE_ACCESS_TOKENS);
            Session session = Session.getActiveSession();
            if (session == null) {
                if (savedInstanceState != null) {
                    session = Session.restoreSession(this, null, statusCallback,
                            savedInstanceState);
                }
                if (session == null) {
                    session = new Session(this);
                }
                Session.setActiveSession(session);
                if (session.getState().equals(SessionState.CREATED_TOKEN_LOADED)) {
                    session.openForRead(new Session.OpenRequest(this)
                            .setCallback(statusCallback));
                }
            }
            updateView();

@Override
    public void onStart() {
        super.onStart();
        Session.getActiveSession().addCallback(statusCallback);
    }

    @Override
    public void onStop() {
        super.onStop();
        Session.getActiveSession().removeCallback(statusCallback);
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        Session.getActiveSession().onActivityResult(this, requestCode,
                resultCode, data);
    }

    @Override
    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        Session session = Session.getActiveSession();
        Session.saveSession(session, outState);
    }

    private void updateView() {
        Session session = Session.getActiveSession();
        Log.i("session log", session.toString());
        if (session.isOpened()) {
            TextView welcome = (TextView) findViewById(R.id.welcome);
            welcome.setText("Hello !");
        } else {

            doLogin();
        }
    }

    private void doLogin() {
        Session session = Session.getActiveSession();
        if (!session.isOpened() &amp;&amp; !session.isClosed()) {
            session.openForRead(new Session.OpenRequest(this)
                    .setCallback(statusCallback));
        } else {
            Session.openActiveSession(this, true, statusCallback);
        }
    }

    private class SessionStatusCallback implements Session.StatusCallback {
        @Override
        public void call(Session session, SessionState state,
                Exception exception) {
            updateView();
        }
    }
</code></pre>
