Examine source code of igReceipts

{
  "manifest_version": 2,
  "name": "igreceipts",
  "description": "See who's following (and unfollowing) who on Instagram 💅",
  "version": "1.4.1",
  "icons": {
    "16": "icon/16.png",
    "32": "icon/32.png",
    "48": "icon/48.png",
    "96": "icon/96.png",
    "128": "icon/128.png"
  },
  "permissions": [
    "downloads",
    "activeTab",
    "tabs",
    "https://*.fbcdn.net/*",
    "https://*.cdninstagram.com/*"
  ],
  "content_security_policy": "script-src 'self'; object-src 'self'; img-src 'self' data: https://*.fbcdn.net https://*.cdninstagram.com;",
  "browser_specific_settings": {
    "gecko": {
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      },
      "id": "{9d9a154a-a6f6-4339-81a0-96b387021469}"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_title": "igReceipts",
    "default_popup": "popup.html"
  },
  "sidebar_action": {
    "default_panel": "sidepanel.html",
    "default_title": "igReceipts"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.instagram.com/*"
      ],
      "js": [
        "content-scripts/content.js"
      ]
    }
  ]
}