Link control rich preview - improve image placeholder

[getdave]

What problem does this address?

In #31464 @javierarce mentioned the following...

Currently, if an image in the <LinkContorl> rich preview isn't available we show a placeholder. However, it may not be clear that this is a placeholder.

What is your proposed solution?

To improve this we can add the URL to the placeholder as shown in this mockup

https://www.figma.com/file/OXOmvYcX0Gpwgt7FB5LlKA/Rich-URL-metadata?node-id=152%3A0

[mtias]

@getdave @javierarce I'm also noticing that rendering a big placeholder for image and text is a bit annoying when the result cannot retrieve a preview, which seems to happen often. It seems it'd be better to only have a placeholder on the icon and then expand if there is image and description, instead of collapsing when there isn't, which seem odd.

[javierarce]

That was the initial idea, but there was an issue (described here) where the popup moved suddenly when new content appeared.

[mtias]

Ah, I see! Now we have the jump in the other direction in some cases. We should look at addressing it in the popover. I don't when it'd be not disorienting to have a rendered popover reposition itself when its content updates if there's no resize / scroll.

[getdave]

I seem to recall that Popover is due a major refactor or replacement in the near future. Was there someone working on that? I can't quite recall. Perhaps @javierarce or @jasmussen would know?

[mtias]

@diegohaz was looking into it

[getdave]

The placeholder now no longer appears if there is no image retrieved. See #32547.

Closing.