Examine source code of Spotify Notifications Lightweight

{
  "name": "Spotify Notifications Lightweight",
  "version": "1.0.0",
  "author": "ViaxCo & albertfc (forked by ofoo)",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "js": [
        "content.js"
      ],
      "matches": [
        "https://open.spotify.com/*"
      ]
    }
  ],
  "description": "Displays notifications when song changes on Spotify. This is a lightweight fork of https://addons.mozilla.org/en-US/firefox/addon/spotify-notifications/ with tabs and scripting permissions removed along with related functionality. As such first time installation requires simply reloading the spotify page instead.",
  "host_permissions": [
    "https://open.spotify.com/*"
  ],
  "icons": {
    "16": "icon-16.png",
    "32": "icon-32.png",
    "48": "icon-48.png",
    "128": "icon.png"
  },
  "manifest_version": 3,
  "permissions": [
    "notifications"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "@firefox-spotify-notifications-lightweight.ofoo",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}