Examine source code of Centered icon

{
  "manifest_version": 2,
  "name": "Centered icon",
  "version": "1.0",
  "description": "The center icon is an icon that represents the action of centering content, usually text, images, or blocks of content horizontally within a container.",
  "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": "{bef0a452-e594-4b43-af5f-e9ee25702802}"
    }
  }
}