web/web_editor_background_color/static/src/xml/colorpicker.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- Copyright 2017 Jairo Llopis <jairo.llopis@tecnativa.com>
     License LGPL-3.0 or later (http://www.gnu.org/licenses/lgpl). -->

<templates>

    <t t-extend="web_editor.colorpicker">
        <t t-jquery="colorpicker" t-operation="append">
            <div
                class="o_colorpicker_section"
                data-name="custom_color"
                data-icon-class="fa fa-code">
                <input type="text" class="form-control" />
            </div>
        </t>
    </t>

</templates>