Examine source code of Youtube Audio

{
  "manifest_version": 2,
  "name": "YouTube Audio",
  "description": "Listen to YouTube and YouTube Music without downloading video.",
  "version": "1.0.4",
  "icons": {
    "16": "icon/16.png",
    "32": "icon/32.png",
    "48": "icon/48.png",
    "96": "icon/96.png",
    "128": "icon/128.png"
  },
  "browser_action": {
    "default_icon": {
      "16": "icon/16.png",
      "32": "icon/32.png"
    },
    "default_title": "YouTube Audio",
    "default_popup": "popup.html"
  },
  "permissions": [
    "tabs",
    "webRequest",
    "webRequestBlocking",
    "storage",
    "downloads",
    "*://*.youtube.com/*",
    "*://*.youtube-nocookie.com/*",
    "*://music.youtube.com/*",
    "*://m.youtube.com/*",
    "*://*.googlevideo.com/*",
    "https://sponsor.ajay.app/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{580efa7d-66f9-474d-857a-8e2afc6b1181}",
      "strict_min_version": "128.0",
      "data_collection_permissions": {
        "required": [
          "websiteContent"
        ]
      }
    },
    "gecko_android": {}
  },
  "background": {
    "persistent": true,
    "scripts": [
      "background.js"
    ]
  },
  "options_ui": {
    "open_in_tab": true,
    "page": "options.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.youtube.com/*",
        "*://*.youtube-nocookie.com/*",
        "*://music.youtube.com/*",
        "*://m.youtube.com/*"
      ],
      "run_at": "document_start",
      "js": [
        "content-scripts/content.js"
      ]
    }
  ]
}