"Maximize your screen space by controlling the presence of Firefox window Title-bar (Caption) & borders!", to be like Chrome Browser. - Hide FF's caption with 'smart' options, *optional* custom caption & resizers. - Works with ChromiFox-like themes.
Hide title bar if window is maximized.
This extension created only for GNOME 3. It can create problems with another DE (KDE, XFCE, etc). However, you can use HTitle at your own risk (need enable "legacy" mode on settings page).