Examine source code of Timeline Tracker for YouTube

{
  "manifest_version": 3,
  "name": "Timeline Tracker for YouTube",
  "version": "1.0.0",
  "description": "Privately remembers where you left off in YouTube videos — a local timeline that survives even when YouTube history is disabled.",
  "icons": {
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "timelinetracker-youtube@local.extension",
      "strict_min_version": "140.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    },
    "gecko_android": {
      "strict_min_version": "142.0"
    }
  },
  "permissions": [
    "storage",
    "tabs"
  ],
  "host_permissions": [
    "*://*.youtube.com/*"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "action": {
    "default_title": "Timeline Tracker for YouTube",
    "default_popup": "popup/popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.youtube.com/*"
      ],
      "exclude_matches": [
        "*://music.youtube.com/*"
      ],
      "js": [
        "content.js"
      ],
      "css": [
        "content.css"
      ],
      "run_at": "document_idle",
      "all_frames": false
    }
  ]
}