mail-addons/mail_archives/views/templates.xml

<?xml version="1.0" ?>
<openerp>
    <data>
        <template
            id="res_partner_mails_count_assets_backend"
            name="res_partner_mails_count_assets_backend"
            inherit_id="web.assets_backend"
        >
            <xpath expr="." position="inside">
                <link
                    rel="stylesheet"
                    href="/mail_archives/static/src/css/archives.css"
                />
                <script
                    src="/mail_archives/static/src/js/archives.js"
                    type="text/javascript"
                />
            </xpath>
        </template>
    </data>
</openerp>