Examine source code of Reading Mode Toggle yu

{
  "manifest_version": 2,
  "name": "Reading Mode Toggle",
  "version": "1.0",
  "description": "Toggle a clean reading mode using Readability on any webpage.",
  "permissions": [
    "activeTab",
    "tabs"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": "icon.png",
    "default_title": "Reading Mode"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{af2e7a66-2d55-4536-a7d5-f5043f67cee9}"
    }
  }
}