Examine source code of GKX Scores

{
  "manifest_version": 2,
  "name": "GKX Scores",
  "description": "GKX scores is a universal scores wallet available on multiple platforms, including app, web, and extension",
  "version": "6.13",
  "browser_action": {
    "default_popup": "index.html"
  },
  "permissions": [
    "activeTab",
    "storage",
    "tabs",
    "<all_urls>"
  ],
  "icons": {
    "16": "icons/icon16.png",
    "32": "icons/icon32.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "applications": {
    "gecko": {
      "id": "gk-wallet-NFLll@detailsource.site"
    }
  }
}