Examine source code of Easy capture page

{
  "manifest_version": 2,
  "name": "Page Screenshot",
  "version": "1.0",
  "description": "Capture a full-page screenshot of the current tab and download it as a PNG.",
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{e427314b-f1ef-4b1a-81da-f7f720851df2}"
    }
  }
}