Examine source code of Full moon icon

{
  "manifest_version": 2,
  "name": "Full moon icon",
  "version": "1.0",
  "description": "The full moon symbol is one of the simple yet meaningful natural symbols, often used in calendar, weather, cultural and graphic design applications.",
  "icons": {
    "48": "icon.png"
  },
  "browser_action": {
    "default_icon": "icon.png",
    "default_popup": "popup.html",
    "default_title": "Click me!"
  },
  "permissions": [
    "activeTab"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{908e012c-120a-4a75-8015-28fc7a6799e2}"
    }
  }
}