Examine source code of Copy as PNG

{
  "manifest_version": 2,
  "name": "Copy as PNG",
  "version": "1.0.2",
  "description": "Copy any image on the 'net as PNG",
  "permissions": [
    "menus",
    "clipboardWrite",
    "scripting",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "main.js"
    ],
    "persistent": false
  },
  "icons": {
    "48": "res/png-icon-light.svg",
    "96": "res/png-icon-light.svg"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{5439b5b1-3d66-4216-89e4-fa943c30e049}"
    }
  }
}