Package: chromium Version: 62.0.3202.89-1~deb9u1 In full screen mode ^l key does not work and the search and address box from the default home page doesn't work either. In Firefox both work: the search box in the home page actually searches from that box and the address bar and tabs pop up with ^l (without the menu bar, window manager decorations and desktop panel, of course), and quite frankly, that's what you expect since entering addresses and searches are quite common and necessary also in full screen mode.
Although in chromium there's no menu bar and the window title bar is integrated into the tabs bar, I still think address and searches entering still make sense without exiting the mode since (1) it's also necessary to enter addresses and searches in full screen and cumbersome exiting and entering the mode again, and (2) desktop panel would remain hidden anyway. I would opt for temporarily showing address and tab bars and switching cursor to the address bar. Once an address or search is entered or ESC pressed or the page clicked the helper bars should get hidden again. If it's tabs what the user wanted, and clicking on the page or pressing ESC seems to be not very intuitive, a banner can be shown instructing to press ESC or click in the page to hide the address bar and tabs, much like it is shown when entering full screen mode to exit from it. Please, forward to upstream if necessary.