Examine source code of SF Shock Bridge Theme

{
  "description": "A dynamic Firefox theme made for San Francisco Shock fans. Reskins the browser based on time of day.",
  "manifest_version": 2,
  "name": "Shock Theme",
  "permissions": [
    "alarms",
    "tabs",
    "theme"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "version": "1.0",
  "browser_specific_settings": {
    "gecko": {
      "strict_min_version": "55.0a2"
    }
  }
}