Examine source code of Brightness Control v2

{
  "manifest_version": 2,
  "name": "Brightness Control",
  "version": "1.0",
  "description": "Adjust the brightness of webpages for comfortable reading.",
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_icon": "icons/brightness-48.png",
    "default_popup": "popup.html",
    "default_title": "Adjust Brightness"
  },
  "icons": {
    "48": "icons/brightness-48.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{0c4f8017-536b-4b89-ace0-3e73b53818b0}"
    }
  }
}