Examine source code of SaveUnder

{
  "manifest_version": 3,
  "name": "SaveUnder",
  "version": "1.0",
  "description": "Speichere Grafiken unter dem Mauszeiger, auch wenn sie überlagert sind.",
  "permissions": [
    "contextMenus",
    "scripting",
    "downloads",
    "activeTab"
  ],
  "host_permissions": [
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "icons": {
    "48": "icon.png"
  },
  "action": {
    "default_icon": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "saveunderV3@youknowwhodoesyouknowwhat"
    }
  }
}