New names should according to spec be :

• sec-ch-dpr
• sec-ch-width
• sec-ch-viewport-width

See https://github.com/imgeng/image-cdn-wordpress/blob/master/imageengine/class-imagecdn.php#L28 and https://github.com/imgeng/image-cdn-wordpress/blob/master/imageengine/class-imagecdn.php#L46

The corresponding permissions policy header (

) should strip the sec- prefix while constructing the permissions-policy header.

The feature-policy header can be removed:

Acceptance criteria:

Response header accept-ch looks like this:
Accept-CH: sec-ch-width, sec-ch-viewport-width, sec-ch-dpr

Response header permissions-policy looks like this:
permissions-policy: ch-width=("<ie-delivery-address-goes-here>"),ch-viewport-width=("<ie-delivery-address-goes-here>"),ch-dpr=("<ie-delivery-address-goes-here>")