Examine source code of WebCapture Pro

{
  "manifest_version": 2,
  "name": "Screenshot Extension",
  "description": "Captures screenshots of webpages",
  "version": "1.0",
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{8b70d7f0-c1e8-4cc6-979e-3fa47abc3113}"
    }
  }
}