Examine source code of New theme icons

{
  "manifest_version": 2,
  "name": "New theme icons",
  "version": "1.0",
  "description": "New topic icons can also have many meanings depending on the context in which they are used. Here are some common icons that are often used to represent new topics, especially in user interfaces, forums, applications, or documentation.",
  "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": "{a4838620-ade7-496d-ae9b-1e65ce34daa4}"
    }
  }
}