manifest.json

{
  "name": "copyText",
  "version": "1.0",
  "manifest_version": 3,
  "description": "Copy text / page source",
  "permissions": ["scripting"],
  "host_permissions": [
    "http://*/*",
    "https://*/*"
  ],
  "action": {
    "default_icon": "icon19.png",
    "default_title": "Copy text",
    "default_popup": "popup.html"
  }
}