Mode: force_next
Version: 54.0.2798.0
Reproduction Steps: 
1. Launch Chromevox Next
2. Alt+Shift+S
3. CVox+Right arrow past cast devices to mute button.
Expected: Mute button is focusable in this manner and by pressing tab and shift+tab.
Actual: Button is unlabeled, and pressing tab would not alert a user to the presence of that button. This makes it difficult for both a screen reader user and users that rely on various other technologies, such as switch devices.