Examine source code of Daily Image Viewer

{
  "manifest_version": 2,
  "name": "Daily Image Viewer",
  "version": "1.0",
  "description": "Displays a new image each day.",
  "icons": {
    "48": "icon.png"
  },
  "permissions": [
    "storage"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{0775b691-f520-4c87-a546-c4de19c4e66d}"
    }
  }
}