Examine source code of InstaFollowCheck

{
  "manifest_version": 2,
  "name": "InstaFollowCheck",
  "version": "1.1",
  "description": "Compares followers and following lists.",
  "permissions": [
    "tabs"
  ],
  "browser_action": {
    "default_title": "InstaFollowCheck",
    "default_popup": "index.html"
  },
  "content_scripts": [
    {
      "matches": [
        "https://www.instagram.com/*/followers/"
      ],
      "js": [
        "scripts/followers.js"
      ]
    },
    {
      "matches": [
        "https://www.instagram.com/*/following/"
      ],
      "js": [
        "scripts/following.js"
      ]
    }
  ],
  "background": {
    "scripts": [
      "scripts/background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{59924346-a534-42e9-a66f-66c8eedd9457}"
    }
  }
}