Examine source code of Apple-Music-RPC

{
  "manifest_version": 2,
  "name": "Apple-Music-RPC",
  "version": "1.0",
  "description": "Discord Rich Presence for Apple Music",
  "icons": {
    "48": "icons/48.png"
  },
  "permissions": [
    "*://127.0.0.1/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://music.apple.com/*"
      ],
      "js": [
        "index.js"
      ]
    }
  ]
}