mail-addons/mail_check_immediately/views.xml

<openerp>
    <data>
        <template id="assets_backend_inherited_check_mail" name="Check mail immediately bar" inherit_id="web.assets_backend">
            <xpath expr="." position="inside">
                <script type="text/javascript" src="/mail_check_immediately/static/src/js/main.js"></script>
            </xpath>
        </template>
    </data>
</openerp>