Examine source code of Do Not Disturb Icon

{
  "manifest_version": 2,
  "name": "Do Not Disturb Icon",
  "version": "1.0",
  "description": "The do not disturb icon is commonly used to indicate a silent state, to avoid being disturbed or to mute notifications.",
  "icons": {
    "48": "icon.png"
  },
  "browser_action": {
    "default_icon": "icon.png",
    "default_popup": "popup.html",
    "default_title": "Click me!"
  },
  "permissions": [
    "activeTab"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{4edf33a0-f2c6-4c3a-9e90-88b942186508}"
    }
  }
}