Examine source code of HN Pop-up

{
  "name": "Hacker News User Link Pop-up",
  "version": "3.0",
  "description": "Hover on a Hacker News user link to see their profile",
  "manifest_version": 2,
  "permissions": [
    "https://news.ycombinator.com/*",
    "https://hacker-news.firebaseio.com/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://news.ycombinator.com/*"
      ],
      "js": [
        "main.js"
      ]
    }
  ],
  "icons": {
    "16": "icon16.png",
    "48": "icon48.png",
    "64": "icon64.png",
    "128": "icon128.png",
    "256": "icon256.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{321b0989-8f8f-460d-ace4-3ede299264de}"
    }
  }
}