Many sites are structured on top of multiple subdomains, examples include:

1. eCommerce - example use cases:

a. Site sections: Structuring different parts of the site on subdomains, such as www.site.com, for Home, listings.site.com for Listings, product.site.com for Product Pages, etc.
b. User Flow: Separating different parts of the purchase flow (checkouts, sign-in, etc) from the main domain. For example, using secure.site.com, or checkout.site.com to separate the booking and user account management pages, from the rest of the site.

2. News: Subdomains can be used to structure the information architecture of the site. Having, for example the main site at: www.site.com, the Sports section at sports.site.com, Politics at politics.site.com, and so forth.

On these cases, when users navigate across the site in fullscreen mode, pages that belong to subdomains will be opened in a CCT.
For site owners, it’s hard to migrate to a single subdomain, to mitigate this, and for users showing a CCT can be a disruptive UX, since they are not aware of the underlying technical aspects of the site, and expect to navigate across the same experience (like in a native app).


Steps to reproduce:
(1) Go to a PWA that has some sections belonging to different subdomains.
(2) Add site to homescreen.
(3) When navigating across sections, if the page belongs to a different subdomain, it will be opened in a CCT.

Expected result:

This is the expected result on Chrome 69. On previous versions of Chrome, it used to show a thin bar at the top.

Actual result:

Ideally users shouldn’t be aware of a change in a subdomain when navigating the PWA in fullscreen mode.