Examine source code of YouTube Playlist Length & Progress Bar

{
  "name": "YouTube Playlist Length & Progress Bar",
  "homepage_url": "https://github.com/stlee42/YouTube-Playlist-Duration-bar/",
  "version": "0.6.7.1",
  "description": "A progress bar to show playlist progress and duration",
  "manifest_version": 3,
  "host_permissions": [
    "*://www.youtube.com/*"
  ],
  "action": {
    "default_popup": "html/popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://www.youtube.com/*"
      ],
      "js": [
        "scripts/content.js"
      ],
      "css": [
        "css/common.css",
        "css/duration-playing.css",
        "css/duration-playlist.css"
      ]
    }
  ],
  "web_accessible_resources": [
    {
      "matches": [
        "*://www.youtube.com/*"
      ],
      "resources": [
        "scripts/duration-playing.js",
        "scripts/duration-playlist.js"
      ]
    }
  ],
  "icons": {
    "16": "icons/icon-16.png",
    "32": "icons/icon-32.png",
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{fd275221-4bad-4558-bf14-79afb62e7008}"
    }
  }
}