Examine source code of Amazon Local Currency

{
  "manifest_version": 2,
  "name": "Amazon Local Currency",
  "description": "Display Amazon prices in your local currency.",
  "author": "Yossi Frances",
  "version": "1.0.3",
  "icons": {
    "16": "icons/16.png",
    "32": "icons/32.png",
    "64": "icons/64.png",
    "96": "icons/96.png",
    "128": "icons/128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.amazon.com/*",
        "*://*.amazon.co.uk/*",
        "*://*.amazon.de/*",
        "*://*.amazon.es/*",
        "*://*.amazon.fr/*",
        "*://*.amazon.it/*",
        "*://*.amazon.co.jp/*"
      ],
      "js": [
        "script.js"
      ]
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_popup": "popup.html"
  },
  "permissions": [
    "activeTab",
    "storage",
    "https://amazon-local-currency.herokuapp.com/"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "amazon-local-currency@yfrans.app",
      "strict_min_version": "57.0"
    }
  }
}