Definition of "chrome"

So, just as a car might have shiny chrome trimming, a bumper, and a grill that cover the vehicle, so the chrome of an OS window surrounds and complements the window itself. Examples of chrome include the title bar, the Minimize/Maximize/Restore buttons, menu bars, and toolbars.

2009, Richard Wagner, Adobe AIR For Dummies‎, John Wiley & Sons

Similarly [to the chrome exterior of an automobile], in most modern GUIs, the chrome lives around the edges of the screen, surrounding the middle area, which is dedicated to the user's data.

2012 January 29, Jakob Nielsen, “Browser and GUI Chrome”, in Nielsen Norman Group homepage‎, Nielsen Norman Group, archived from the original on 2013-03-07

I had the idea of making our browser chrome match the actual hardware you were on. If your Mac’s bezel was Bondi blue, we’d make our UI Bondi blue.

2020 January 4, Jimmy Grewal, quoting Maf Vosburgh, “Internet Explorer 5 for Mac: twentieth anniversary”, in Jimmy's Blog‎, archived from the original on 2020-01-09

Disrespect my nigga Boss and I'm flashin' the chrome

2012, “Ali Bomaye”, in Jesus Piece, performed by The Game

I ain't trippin' long 'cause I can reach the chrome / Heat your home like Southern California Gas, police pass

2013, “Hive”, in Doris, performed by Earl Sweatshirt