Examine source code of HN mark as read

{
  "manifest_version": 2,
  "name": "HNRead",
  "version": "1.1.1",
  "description": "Adds a button to mark a thread as read on HN",
  "icons": {
    "48": "hacker-news.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://news.ycombinator.com/*"
      ],
      "js": [
        "hnread.js"
      ],
      "css": [
        "hnread.css"
      ]
    }
  ]
}