Examine source code of Remove Whatsapp Avatars

{
  "manifest_version": 2,
  "name": "Remove Whatsapp Avatars",
  "version": "1.0",
  "description": "Remove all avatars of groups of Whatsapp Web",
  "icons": {
    "48": "icons/remove-avatars-icon-48px.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.whatsapp.com/*"
      ],
      "js": [
        "main.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{c20b1628-5570-468f-8308-6d76548a7300}"
    }
  }
}