In short: Google's unified Android-like system tray with a dark theme has finally arrived on Chrome OS's Stable Channel, as spotted by at least one observant user at Reddit. The change eliminates the need for a second shelf area for notifications, hidden under the bell icon. Instead, notifications in the opposite position to where they appear on the search giant's mobile OS. More succinctly, new notifications appear above the Quick Settings, user profile image, and system controls found on the right-hand side of the shelf, opposite the app drawer. Those are both scrollable and collapsible with a 'clear all' button placed at the bottom.
Background: This is not the first time this system tray change has been observed and the dark variant of the UI has been in the works since at least February. However, over that period, it was always seen in developer-specific channels of Chrome OS, rather than in the user-ready Stable Channel. What's more, the modern take on the design rounds off all of the edges of the system tray itself once clicked, bringing the interface much more in line with the latest Material Design standards. The background of Quick Settings icons, meanwhile, switch to a blue rounded style when turned on and the whole tray is collapsible, in almost exactly the same way as it is in Android. Having said that, accessing the new settings still requires a flag menu item to be altered. Specifically, users who want to check out the setting will need to navigate to "chrome://flags" and search the page for "#enable-system-tray-unified." That line item must be set to "Enabled" from its default state and then the system will need to reset. To switch back, that same item must be returned to "default."
Impact: Because the new UI has been moved to the Stable Channel, it's not unreasonable to presume that Google plans to make it the default setting at some point in the near future. In fact, that could happen as early as Chrome OS version 70. Bearing that in mind, further changes could be made to the UI before that happens and there's no guarantee that it will keep its dark coloration or that Google will let users choose from a dark or light theme.