Examine source code of e621downloader

{
  "description": "Download and scrape e621 pools and etc.",
  "manifest_version": 2,
  "name": "e621downloader",
  "version": "1.3.2",
  "homepage_url": "https://github.com/Yusifx1/e621-userscript-and-extension",
  "icons": {
    "48": "icons/e621-48.png"
  },
  "permissions": [
    "*://*.furaffinity.net/*",
    "downloads"
  ],
  "background": {
    "page": "background.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://e621.net/*",
        "*://e926.net/*"
      ],
      "js": [
        "content.js"
      ]
    }
  ]
}