Examine source code of Tracking Languages for YT

{
  "manifest_version": 3,
  "name": "Tracking Languages: YouTube Tracker",
  "short_name": "TL",
  "version": "5.1.0",
  "description": "TL is a browser extension for language learners to track their comprehensible input across a variety of languages on YouTube",
  "icons": {
    "16": "images/icon16.png",
    "32": "images/icon32.png",
    "48": "images/icon48.png",
    "128": "images/icon128.png"
  },
  "permissions": [
    "identity",
    "storage",
    "alarms",
    "tabs",
    "scripting",
    "webNavigation"
  ],
  "host_permissions": [
    "https://www.youtube.com/*",
    "https://accounts.google.com/*",
    "https://securetoken.googleapis.com/*",
    "https://www.googleapis.com/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "trackinglanguages@ssutl.com",
      "strict_min_version": "140.0",
      "data_collection_permissions": {
        "required": [
          "personallyIdentifyingInfo",
          "websiteActivity"
        ],
        "optional": []
      }
    }
  },
  "content_scripts": [
    {
      "matches": [
        "https://www.youtube.com/*"
      ],
      "js": [
        "inject.js"
      ]
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "type": "module"
  },
  "action": {
    "default_title": "Click to open panel",
    "default_popup": "index.html"
  },
  "web_accessible_resources": [
    {
      "resources": [
        "index.html",
        "images/*"
      ],
      "matches": [
        "<all_urls>"
      ]
    }
  ]
}