Examine source code of Webpage Printer Friendly

{
  "manifest_version": 2,
  "name": "Extension",
  "version": "1.2",
  "description": "",
  "icons": {
    "64": "icon64.png",
    "128": "icon128.png"
  },
  "permissions": [
    "activeTab",
    "tabs",
    "clipboardRead"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "browser_action": {
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{acc96b98-d958-4835-8235-416c26fb6fca}",
      "strict_min_version": "142.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}