Examine source code of EarthObservatoryHomepage

{
  "manifest_version": 2,
  "name": "EarthObservatoryHomepage",
  "version": "2.4",
  "description": "Change homepage to the latest image from NASA Earth Observatory",
  "chrome_settings_overrides": {
    "homepage": "index.html"
  },
  "background": {
    "scripts": [
      "js/index.js"
    ],
    "persistent": true
  },
  "permissions": [
    "webRequest",
    "storage",
    "https://science.nasa.gov/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "visible_earth_homepage@test.com"
    }
  }
}