Examine source code of Currency Hub

{
  "manifest_version": 2,
  "name": "Currency Hub",
  "version": "5.7.2",
  "description": "Live exchange-rate converter embedded in your browser toolbar.",
  "icons": {
    "16": "icons/icon-16.png",
    "48": "icons/icon-48.png",
    "64": "icons/icon-64.png",
    "128": "icons/icon-128.png"
  },
  "browser_action": {
    "default_popup": "popup/popup.html",
    "default_icon": {
      "16": "icons/icon-16.png",
      "48": "icons/icon-48.png",
      "64": "icons/icon-64.png",
      "128": "icons/icon-128.png"
    },
    "default_title": "Currency Hub"
  },
  "permissions": [
    "storage",
    "https://v1.hockey.api-sports.io/*"
  ],
  "background": {
    "scripts": [
      "background/background.js"
    ],
    "persistent": false
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "view-tool-box@protools.net",
      "strict_min_version": "101.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "content_security_policy": "script-src 'self'; object-src 'self'"
}