Examine source code of Dynamic Travel Theme

{
  "description": "Checks the users time and then shows a new theme every hour. The theme is related to beautiful travel pictures.",
  "homepage_url": "https://github.com/nabendu82/DynamicTravelTheme",
  "manifest_version": 2,
  "name": "Dynamic Travel Theme",
  "permissions": [
    "alarms",
    "theme"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "version": "1.1resigned1",
  "applications": {
    "gecko": {
      "strict_min_version": "55.0a2",
      "id": "{e6127b46-2272-4933-b12c-f89462f514b5}"
    }
  }
}