Examine source code of Limited space icon

{
  "manifest_version": 2,
  "name": "Limited space icon",
  "version": "1.0",
  "description": "The confined space symbol is used to warn of hazardous areas, especially in industrial, construction, or engineering systems, or confined spaces such as in automobiles...",
  "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": "{15b39e94-9f30-4e58-bdef-114c7b7cb3a9}"
    }
  }
}