Examine source code of NowPlaying.Site Extension

{
  "manifest_version": 3,
  "name": "NowPlaying.Site Extension",
  "version": "3.0.9",
  "description": "Implements a client to send the current active listener to the NowPlaying widget",
  "author": "NowPlaying.Site",
  "browser_specific_settings": {
    "gecko": {
      "id": "hetisjoey15@gmail.com",
      "strict_min_version": "109.0"
    }
  },
  "background": {
    "service_worker": "background.js",
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "tabs",
    "storage"
  ],
  "host_permissions": [
    "https://*.youtube.com/*",
    "https://*.soundcloud.com/*",
    "https://play.pretzel.rocks/*",
    "https://*.epidemicsound.com/*",
    "https://www.deezer.com/*",
    "https://listen.tidal.com/*",
    "https://tidal.com/*",
    "https://music.apple.com/*"
  ],
  "action": {
    "default_popup": "/interface/popup/index.html",
    "default_title": "NowPlaying.Site Extension",
    "default_icon": {
      "16": "/icons/16.png",
      "32": "/icons/32.png",
      "48": "/icons/48.png",
      "128": "/icons/128.png"
    }
  },
  "options_ui": {
    "page": "/interface/options/index.html",
    "open_in_tab": true
  },
  "content_scripts": [
    {
      "matches": [
        "https://www.youtube.com/*"
      ],
      "js": [
        "/content/youtube.js"
      ]
    },
    {
      "matches": [
        "https://*.soundcloud.com/*"
      ],
      "js": [
        "/content/soundcloud.js"
      ]
    },
    {
      "matches": [
        "https://music.youtube.com/*"
      ],
      "js": [
        "/content/youtube_music.js"
      ]
    },
    {
      "matches": [
        "https://*.epidemicsound.com/*"
      ],
      "js": [
        "/content/epidemicsound.js"
      ]
    },
    {
      "matches": [
        "https://www.deezer.com/*"
      ],
      "js": [
        "/content/deezer.js"
      ]
    },
    {
      "matches": [
        "https://play.pretzel.rocks/*"
      ],
      "js": [
        "/content/pretzel.js"
      ]
    },
    {
      "matches": [
        "https://listen.tidal.com/*"
      ],
      "js": [
        "/content/tidal.js"
      ]
    },
    {
      "matches": [
        "https://tidal.com/*"
      ],
      "js": [
        "/content/tidal.js"
      ]
    },
    {
      "matches": [
        "https://music.apple.com/*"
      ],
      "js": [
        "/content/apple_music.js"
      ]
    }
  ],
  "icons": {
    "16": "/icons/16.png",
    "32": "/icons/32.png",
    "48": "/icons/48.png",
    "128": "/icons/128.png"
  }
}