Examine source code of Save as Markdown

{
  "name": "Save as Markdown",
  "version": "1.0.9",
  "description": "Save current page as Markdown",
  "homepage_url": "https://github.com/leloctai/savemd",
  "manifest_version": 2,
  "applications": {
    "gecko": {
      "id": "savemd@webext.leloctai",
      "strict_min_version": "67.0"
    }
  },
  "icons": {
    "128": "icon.png"
  },
  "permissions": [
    "<all_urls>",
    "activeTab",
    "tabs",
    "downloads",
    "storage",
    "contextMenus"
  ],
  "browser_action": {
    "default_title": "Save as Markdown",
    "default_popup": "popup.html",
    "default_icon": {
      "128": "icon.png"
    }
  },
  "options_ui": {
    "chrome_style": true,
    "page": "options.html"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ]
}