Examine source code of YT Speed

{
  "manifest_version": 3,
  "name": "YT Speed",
  "version": "1.2",
  "description": "Quick speed controls for YouTube — auto-resets on video click. With screenshot feature.",
  "icons": {
    "48": "icon.png",
    "128": "icon128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "yt-speed@meinaddon.de",
      "strict_min_version": "140.0"
    }
  },
  "permissions": [
    "activeTab",
    "tabs",
    "downloads",
    "storage"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "action": {
    "default_popup": "popup.html",
    "default_icon": "icon.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.youtube.com/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ]
}