{
  "manifest_version": 2,
  "name": "Himawari 8 Satellite New Tab Page",
  "short_name": "Himawari 8",
  "description": "Experience the latest image of Earth from the Himawari 8 satellite every time you open a new tab.",
  "version": "0.9.1",
  "homepage_url": "https://github.com/domoritz/himawari-8-chrome",
  "applications": {
    "gecko": {
      "strict_min_version": "54.0"
    }
  },
  "chrome_url_overrides" : {
    "newtab": "index.html"
  },
  "permissions": [
    "storage"
  ],
  "offline_enabled": true,
  "icons": {
    "128": "icons/icon128.png",
    "48":"icons/icon48.png",
    "16":"icons/icon16.png"
  },
  "options_ui": {
    "page": "options.html",
    "chrome_style": true
  }
}

Add manifest for Firefox, which is not compatible with Chrome :-(
Add manifest for Firefox, which is not compatible with Chrome :-(