Examine source code of Free medium

{
  "manifest_version": 2,
  "name": "Free medium extension",
  "version": "1.0.0",
  "description": "Read the premium medium articles free",
  "permissions": [
    "tabs",
    "notifications",
    "https://medium.com/*"
  ],
  "background": {
    "scripts": [
      "scripts/script.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_icon": {
      "128": "images/icon-128.png"
    }
  },
  "icons": {
    "16": "images/icon-16.png",
    "32": "images/icon-32.png",
    "48": "images/icon-48.png",
    "128": "images/icon-128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "freemedium@mozilla"
    }
  }
}