Examine source code of Spotify Notifications

{
  "author": "ViaxCo & albertfc",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "js": [
        "content.js"
      ],
      "matches": [
        "https://open.spotify.com/*"
      ]
    }
  ],
  "description": "Displays notifications when song changes on Spotify.",
  "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,
  "name": "Spotify Notifications",
  "permissions": [
    "notifications",
    "tabs",
    "scripting"
  ],
  "version": "1.0.0",
  "browser_specific_settings": {
    "gecko": {
      "id": "firefox-spotify-notifications@albertfc"
    }
  }
}