Examine source code of Don't slack-redir links

{
  "name": "Don't slack-redir links",
  "description": "An efficient way to prevent Slack from replacing links with slack-redir.net, while still protecting privacy (against referrer leakage).",
  "version": "1",
  "manifest_version": 2,
  "content_scripts": [
    {
      "run_at": "document_end",
      "js": [
        "contentscript.js"
      ],
      "matches": [
        "*://*.slack.com/*"
      ]
    }
  ],
  "icons": {
    "48": "logo.svg"
  },
  "web_accessible_resources": [
    "cleanlink.js"
  ],
  "applications": {
    "gecko": {
      "id": "dont-slack-redir@robwu.nl"
    }
  }
}