Close Tabs Result
The result of invoking a "close tabs" command.
If `FirefoxAccount::close_tabs` is called with more URLs than can fit into a single command payload, the URLs will be chunked and sent in multiple commands.
Chunking breaks the atomicity of a "close tabs" command, but reduces the number of these commands that FxA sends to other devices. This is critical for platforms like iOS, where every command triggers a push message that must show a user-visible notification.