Note that  Issue 799835  tracks standardising on the origin across all installability surfaces, including the desktop PWA window frame. All other surfaces show the origin, so just changing the window frame would be inconsistent and it would be good to have a solid reason for the inconsistency.

Ah OK, interesting.

So it *was* ETLD+1 but r542763 (which added the animation) changed to origin, which was by agreement at the time (see  Issue 809794 ).

Looks like Dom has completed an effort to standardize on origin (per  Issue 799835 ) so we should stick with it, or change all of these surfaces to ETLD+1.

We updated the enamel Guidelines for URL display to standardize on origin:

https://docs.google.com/document/d/1a4aamAaknVXtDkNePPg0ikeAKsJKdWGBND7fFuliChA/edit#

When the primary purpose of displaying a URL is to have the user make a security decision, display the origin. Omit the path, query string, fragment, and any other components of the URL because they provide opportunities for spoofing.
Do not display the scheme if it will always be https://. If the scheme is not https://, prefer to show a security indicator icon (dangerous triangle icon + “Not Secure” string on http://) rather than the scheme itself.
We remove subdomains “www” and “m” as a special case to simplify the origin (except when they are part of the registrable domain).
If in a space-constrained environment, it's acceptable to use registrable domain instead of the full origin.

WontFixing as per #4, though this may be changed in future based on updated advice. :)