Custom header sections show in the Customizer without any choices

[bradyvercher]

The "Previously uploaded" and "Suggested" titles in the "Header Images" section are always showing in the Customizer, even when they don't have any options available. They were hidden when empty in previous versions.

The attached screenshot when using Twenty Fifteen should help clarify.

[bradyvercher]

It looks like this broke in [37476] when the DOM was changed to ​insert a notification container after the title. 38561.diff​ wraps the sections in a container to fix the previous behavior and adds some much needed spacing between the sections.

[westonruter]

@bradyvercher The injection of the notifications container is done as a fallback in case the control didn't include the container itself. So you can add the notifications container to the control's content template to specifically control where it appears.

[bradyvercher]

Thanks @westonruter! 38561.1.diff​ adds the notification container to the header control instead. On closer inspection, that prevents it from being duplicated and injected in the wrong place as well.

[westonruter]

@bradyvercher Your patch looks like it addresses the issue better than the patch on #38366, for which this is actually a duplicate.

[westonruter]

In 39145:

Customize: For Header Image, ensure "Previously uploaded" and "Suggested" headings are hidden when lists are empty.

Fixes regression introduced with the addition of control notifications in [37476]. The container element for notifications is injected after the .customize-control-title element if the .customize-control-notifications-container element does not already exist in the control's template. Also adds missing margin between current image and uploaded images.

Props bradyvercher.
See #34893.
Fixes #38561.

[westonruter]

#38366 was marked as a duplicate.

[westonruter]

#39375 was marked as a duplicate.