Examine source code of Length Unit converter

{
  "manifest_version": 2,
  "name": "lenght Unit converter",
  "description": "This extension will convert the lenght from one unit to other ",
  "version": "1.1resigned1",
  "browser_action": {
    "default_icon": "Refresh.png",
    "default_popup": "popup.html"
  },
  "permissions": [
    "activeTab"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{17093c1a-07a0-4d18-a476-c8ab4e18b7a7}"
    }
  }
}