Examine source code of Quick World Clock

{
  "manifest_version": 2,
  "name": "Quick World Clock",
  "description": "World Clock at a glance in your new tab",
  "homepage_url": "https://www.quickworldclock.com/",
  "background": {
    "scripts": [
      "js/background.js"
    ],
    "persistent": false
  },
  "permissions": [
    "geolocation",
    "storage",
    "https://www.bensendigital.com/quickworldclock/*",
    "https://*.bing.com/*",
    "*://*.google.com/*"
  ],
  "version": "1.1",
  "browser_action": {
    "default_icon": {
      "16": "images/bd-16.png",
      "32": "images/bd-32.png",
      "48": "images/bd-48.png",
      "128": "images/bd-128.png"
    }
  },
  "icons": {
    "16": "images/bd-16.png",
    "32": "images/bd-32.png",
    "48": "images/bd-48.png",
    "128": "images/bd-128.png"
  },
  "chrome_url_overrides": {
    "newtab": "landing.html"
  },
  "web_accessible_resources": [
    "images/*.*"
  ]
}