Examine source code of Copy Extra URL

{
  "manifest_version": 2,
  "name": "CopyExtraURL",
  "version": "2.2",
  "description": "Allows to copy/paste-go an address after domain to/from clipboard",
  "icons": {
    "16": "icons/copy-extra-url-16.png",
    "32": "icons/copy-extra-url-32.png",
    "48": "icons/copy-extra-url-48.png"
  },
  "browser_action": {
    "default_icon": {
      "16": "icons/copy-extra-url-16.png",
      "32": "icons/copy-extra-url-32.png"
    },
    "default_popup": "popup/choose_action.html",
    "default_title": "Address after domain",
    "browser_style": true
  },
  "permissions": [
    "tabs",
    "clipboardRead"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "CopyExtraURL@netcracker.com"
    }
  }
}