Examine source code of Dark Background Preload

{
  "manifest_version": 2,
  "applications": {
    "gecko": {
      "id": "dark-background-preload@qw.thucfb.com",
      "strict_min_version": "60.0"
    }
  },
  "name": "__MSG_extensionName__",
  "version": "0.2resigned1",
  "description": "__MSG_extensionDescription__",
  "permissions": [
    "<all_urls>",
    "storage"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "options_ui": {
    "page": "options.html"
  },
  "default_locale": "en"
}