Examine source code of lookup

{
  "manifest_version": 2,
  "name": "Dictionary Popup",
  "description": "Fetches definitions from Cambridge Dictionary and Glossary of Computer Science",
  "version": "1.0",
  "permissions": [
    "activeTab",
    "https://dictionary.cambridge.org/*",
    "https://en.wikipedia.org/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_end"
    }
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "images/icon16.png",
      "48": "images/icon48.png",
      "128": "images/icon128.png"
    }
  },
  "icons": {
    "16": "images/icon16.png",
    "48": "images/icon48.png",
    "128": "images/icon128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{9111115e-11ce-40e5-91ff-d0c6adfa5d4f}"
    }
  }
}