Before this commit, if you add a background video in a popup, the video
frame will not setup properly because the _adjustIframe function cannot
find wrapperWidth and its ratio.

After this commit, _adjustIframe will be called again once the popup
is opened.

task-2251203

Part-of: odoo/odoo#63634
Co-authored-by: qsm-odoo <qsm@odoo.com>