Earlier quoted context omitted.
The UI logically and visually belongs to the opening app, indeed. If the page itself opens a modal it opens on top of the bar and it's close button closes that modal.
but it's not an "opening app" ... it's a search engine. with links to other sites. ... or is it?
If I hit the search bar on my Android device, and it opens Google Search in an app interface, is it an app, is it a search engine, or is it both? What about with their new strategy of integrating Google Search more closely into apps? How about then?
The line is so blurry as to be irrelevant. The wording on the responses seem to be on a different side of that philosophical argument, but I'm not sure it is that black and white.