"Close requests" are a new concept that encompasses user requests to close something currently open, using the Esc key on desktop or the back gesture/button on Android. Integrating them into Chromium comes with two changes: * CloseWatcher, a new API for directly listening and responding to close requests. * Upgrades to <dialog> and popover="" to use the new close request framework, so that they respond to the Android back button.
An important common feature of various "modal" or "popup" components in web apps is that they are designed to be easy to close, with a uniform interaction mechanism for doing so. Typically, this is the Esc key on desktop platforms, and the back gesture/button on some mobile platforms (notably Android). Currently, web developers have no good way to handle these close requests for their own components. This is especially problematic on Android devices, where the back gesture/button is the traditional close request.
Samples: https://close-watcher-demo.glitch.me
Explainers: https://github.com/WICG/close-watcher/blob/main/README.md