Earlier quoted context omitted.
Please address this question @cramforce. Why are you introducing a new and totally unnecessary display element when the back button is built right in to the browser and everyone already knows how it works? No matter how hard I try, I can't think of any good reason for this banner. But hey, to the right of that X there sure is a lot of room for placing an adsense ad! What a strange co-incidence.
The banner is needed to show the logical origin, given that the browser is still on Google.com and the article is shown in a iframe (to enable pre-rendering). Our native apps do not have this constraint and thus don't have the extra bar. I can't give you a 100% reason for the X. I know multiple UI versions were tested and this did well.
What an amazing coincidence that this great new tech requires users to remain on google.com "for technical reasons".