Examine source code of Musical note icon

{
  "manifest_version": 2,
  "name": "Musical note icon",
  "version": "1.0",
  "description": "Musical note symbols represent Music, songs, melodies, sounds in general.",
  "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": "{cb4c8ef8-1071-4c94-ad94-4d721f401802}"
    }
  }
}