Examine source code of Critical Role HP Tracker

{
  "name": "Critrole HP Tracker",
  "version": "0.5.1",
  "description": "Track current health of players during combats",
  "manifest_version": 3,
  "icons": {
    "128": "icons/CombatTrackerIcon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "critrolehptracker@snappdragonn",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "permissions": [
    "storage"
  ],
  "host_permissions": [
    "*://critrole.com/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://www.youtube.com/*",
        "*://www.twitch.tv/*",
        "*://beacon.tv/*"
      ],
      "all_frames": true,
      "css": [
        "trackerStyle.css"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "web_accessible_resources": [
    {
      "resources": [
        "trackerStyle.css",
        "characterImages/*",
        "hearts/*",
        "icons/*",
        "apiKey.txt"
      ],
      "matches": [
        "*://www.youtube.com/*",
        "*://www.twitch.tv/*",
        "*://beacon.tv/*"
      ]
    },
    {
      "resources": [
        "options.js"
      ],
      "matches": [
        "*://*/*"
      ]
    }
  ],
  "background": {
    "scripts": [
      "serviceWorker.js"
    ]
  }
}