Examine source code of Custom Speed for YouTube

{
  "manifest_version": 3,
  "name": "Custom Speed for YouTube",
  "version": "1.0.1",
  "description": "Set any YouTube playback speed with a native speed menu, keyboard shortcuts, and a compact popup.",
  "action": {
    "default_title": "Custom Speed for YouTube",
    "default_popup": "index.html",
    "default_icon": {
      "16": "icons/icon16.png",
      "32": "icons/icon32.png",
      "48": "icons/icon48.png",
      "128": "icons/icon128.png"
    }
  },
  "icons": {
    "16": "icons/icon16.png",
    "32": "icons/icon32.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "permissions": [
    "storage",
    "tabs"
  ],
  "host_permissions": [
    "https://www.youtube.com/*",
    "https://youtube.com/*",
    "https://www.youtube-nocookie.com/*"
  ],
  "background": {
    "scripts": [
      "assets/serviceWorker.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "https://www.youtube.com/*",
        "https://youtube.com/*",
        "https://www.youtube-nocookie.com/*"
      ],
      "js": [
        "assets/content.js"
      ],
      "css": [
        "assets/content.css"
      ],
      "run_at": "document_idle"
    }
  ],
  "commands": {
    "increase-speed": {
      "suggested_key": {
        "default": "Alt+Shift+Period"
      },
      "description": "Increase YouTube playback speed"
    },
    "decrease-speed": {
      "suggested_key": {
        "default": "Alt+Shift+Comma"
      },
      "description": "Decrease YouTube playback speed"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "custom-speed-for-youtube@treustrasse.com",
      "strict_min_version": "142.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "minimum_chrome_version": "116"
}