Examine source code of Briefcase icon

{
  "manifest_version": 2,
  "name": "Briefcase icon",
  "version": "1.0",
  "description": "TBriefcase icons are often designed to represent work, documents, records, or professionalism – very popular in office applications, app icons, or signage.",
  "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": "{6c73ebc0-a4e9-426d-8877-4980b6942818}"
    }
  }
}