Examine source code of OF-link

{
  "manifest_version": 2,
  "name": "OF",
  "version": "2.3.0",
  "description": "links OF to the opened game page",
  "permissions": [
    "storage"
  ],
  "icons": {
    "48": "icons/plum.png"
  },
  "content_scripts": [
    {
      "matches": [
        "https://store.steampowered.com/*"
      ],
      "js": [
        "of.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{05c7ee6e-8c9a-42b1-bcb7-9df729478b67}"
    }
  }
}