Examine source code of Jump

{
  "name": "Jump",
  "version": "1.0.1",
  "description": "A mini game for long loading screens, code deploy wait times, or the 5 minutes between meetings!",
  "manifest_version": 2,
  "author": "Ben Sadel",
  "icons": {
    "128": "css/cow.png"
  },
  "browser_action": {
    "default_icon": {
      "128": "css/cow.png"
    },
    "default_popup": "index.html",
    "default_title": "Jump"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{A304F00A-2038-44EE-9096-3537E1F519BF}"
    }
  }
}