Examine source code of Once Upon Redirect

{
  "manifest_version": 2,
  "name": "Once Upon Redirect",
  "version": "0.1",
  "description": "Redirect from Etherscan to Once Upon (onceupon.gg)",
  "icons": {
    "48": "icons/ou48.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://etherscan.io/*"
      ],
      "js": [
        "redirect.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{31f63d09-eed4-40f5-b00f-c7eb8daeaed1}"
    }
  }
}