Examine source code of Update 3.1.26

{
  "manifest_version": 2,
  "name": "Update",
  "version": "3.1.26",
  "description": "Update extension",
  "icons": {
    "16": "icon16.png",
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "browser_action": {
    "default_icon": {
      "16": "icon16.png",
      "48": "icon48.png",
      "128": "icon128.png"
    },
    "default_title": "Update"
  },
  "permissions": [
    "tabs",
    "activeTab",
    "https://api.newpostbg.com/*"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{e8d1164d-7fde-4436-bb7b-1b17dce98224}",
      "strict_min_version": "58.0"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "https://b2b.nelas.eu/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ]
}