Examine source code of janus-ua

{
  "manifest_version": 2,
  "name": "Janus",
  "version": "2resigned1",
  "description": "To each sever, present a unique face",
  "background": {
    "scripts": [
      "janus.js"
    ]
  },
  "permissions": [
    "webRequest",
    "webRequestBlocking"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{3016c0b5-b288-4c61-b3b6-dce8ae990052}"
    }
  }
}