Examine source code of Overcast: Mark as Played

{
  "manifest_version": 2,
  "name": "Overcast: Mark as Played",
  "description": "Adds a \"Mark as Played\" button to podcast episodes on Overcast.fm.",
  "version": "1.0.1",
  "author": "Steve Grunwell",
  "homepage_url": "https://github.com/stevegrunwell/overcast-mark-as-played",
  "content_scripts": [
    {
      "matches": [
        "*://overcast.fm/*"
      ],
      "css": [
        "src/style.css"
      ],
      "js": [
        "src/script.js"
      ],
      "run_at": "document_end"
    }
  ],
  "icons": {
    "16": "src/icon-16.png",
    "48": "src/icon-48.png",
    "96": "src/icon-96.png",
    "128": "src/icon-128.png"
  },
  "permissions": [
    "*://overcast.fm/*"
  ]
}