Examine source code of Simon Classic

{
  "manifest_version": 2,
  "name": "__MSG_extensionName__",
  "short_name": "__MSG_extensionName__",
  "author": "Roberto E. Oneto",
  "description": "__MSG_extensionDescription__",
  "version": "1.3.1.0",
  "background": {
    "page": "main.html",
    "persistent": true
  },
  "browser_action": {
    "default_icon": "img/icon.png",
    "default_popup": "popup.html"
  },
  "sidebar_action": {
    "default_title": "Simon",
    "default_panel": "gameSB.html",
    "browser_style": true,
    "default_icon": {
      "16": "img/icon.png",
      "48": "img/icon48.png"
    },
    "open_at_install": false
  },
  "icons": {
    "16": "img/icon.png",
    "48": "img/icon48.png",
    "128": "img/icon128.png"
  },
  "permissions": [
    "https://onets.altervista.org/Simon/",
    "storage"
  ],
  "default_locale": "en",
  "browser_specific_settings": {
    "gecko": {
      "id": "{537de8f8-4de7-4ce3-bd1f-8d77724ef136}"
    }
  }
}