Examine source code of PinPatrol

{
  "manifest_version": 2,
  "name": "PinPatrol",
  "short_name": "PinPatrol for Firefox Quantum",
  "version": "0.4.2resigned1",
  "description": "This table shows, in a readable format, the state of HSTS and HPKP domains stored by the browser.",
  "author": "ElevenPaths",
  "icons": {
    "16": "data/img/icon-16.png",
    "32": "data/img/icon-32.png",
    "64": "data/img/icon-64.png"
  },
  "browser_action": {
    "default_title": "PinPatrol",
    "default_icon": {
      "16": "data/img/icon-16.png",
      "32": "data/img/icon-32.png",
      "64": "data/img/icon-64.png"
    }
  },
  "background": {
    "scripts": [
      "index.js"
    ]
  },
  "permissions": [
    "tabs",
    "history"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "@PinPatrol"
    }
  }
}