Examine source code of Permission Checker

{
  "manifest_version": 2,
  "name": "Permission Checker",
  "version": "1.0",
  "description": "Detect and display permissions requested by websites.",
  "permissions": [
    "tabs",
    "webRequest",
    "*://*/*"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icon.png"
  },
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{064c214d-ac6f-4c36-b951-8199768069c8}"
    }
  }
}