Examine source code of Search Lexico

{
  "manifest_version": 2,
  "name": "Search Lexico",
  "description": "Search Lexico's English dictionary (archived version) by selecting a word and right-clicking.",
  "version": "2.0",
  "developer": {
    "name": "pm"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "contextMenus",
    "activeTab"
  ],
  "icons": {
    "64": "icons/lexico-64.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{c9b4411d-86d6-40ee-b656-445370e44319}"
    }
  }
}