Examine source code of Call Message Icon

{
  "manifest_version": 2,
  "name": "Call Message Icon",
  "version": "1.0",
  "description": "The call and message icons are commonly used to represent common communication functions on phones, messaging apps, or websites.",
  "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": "{36186790-6be9-47f5-90cf-a4467994362a}"
    }
  }
}