Examine source code of Save PDF

{
  "manifest_version": 3,
  "name": "Save PDF",
  "version": "3.0",
  "browser_specific_settings": {
    "gecko": {
      "id": "savepdf@kevinorbie"
    }
  },
  "description": "Enables users to take full-page PDF screenshots containing embedded text info.",
  "homepage_url": "https://github.com/KevinOrbie/save-pdf",
  "permissions": [
    "activeTab",
    "contextMenus",
    "scripting",
    "tabs",
    "storage",
    "unlimitedStorage"
  ],
  "icons": {
    "16": "assets/icons/save-pdf.svg",
    "32": "assets/icons/save-pdf.svg",
    "48": "assets/icons/save-pdf.svg",
    "64": "assets/icons/save-pdf.svg",
    "96": "assets/icons/save-pdf.svg",
    "128": "assets/icons/save-pdf.svg"
  },
  "background": {
    "scripts": [
      "background-script.js"
    ],
    "type": "module"
  },
  "action": {
    "default_icon": "assets/icons/save-pdf.svg",
    "default_title": "Save PDF",
    "default_popup": "popup/popup.html"
  },
  "commands": {
    "save-as-pdf": {
      "suggested_key": {
        "default": "F9"
      },
      "description": "Save this page as PDF file."
    }
  }
}