Examine source code of Desk phone icon

{
  "manifest_version": 2,
  "name": "Desk phone icon",
  "version": "1.0",
  "description": "The landline phone icon is an image representing a landline phone – commonly used in offices or homes before the smartphone era.",
  "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": "{ca36cd12-86a1-4187-bd3c-74252113c447}"
    }
  }
}