Examine source code of Wikipedia Quick Summary

{
  "manifest_version": 2,
  "name": "Wikipedia Quick Summary",
  "version": "1.0",
  "description": "Show Wikipedia summaries in a popup without opening the page",
  "permissions": [
    "activeTab",
    "https://en.wikipedia.org/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{28be385b-a8b3-474f-999c-54ff82d25a41}"
    }
  }
}