Examine source code of Network icon

{
  "manifest_version": 2,
  "name": "Network icon",
  "version": "1.0",
  "description": "Network icons represent connections between devices, internet access, data transmission, or the status of a wireless/wired connection system.",
  "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": "{039d4bf4-5293-408b-8157-851be99fe0d3}"
    }
  }
}