Examine source code of FocusBubble

{
  "manifest_version": 2,
  "name": "FocusBubble",
  "version": "1.0",
  "description": "A minimal extension to help you stay focused by displaying gentle reminders.",
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icon.png"
  },
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{0d4d6ede-740c-4ede-87ef-6c7db6dd87df}"
    }
  }
}