Examine source code of Email icon

{
  "manifest_version": 2,
  "name": "Email icon",
  "version": "1.0",
  "description": "The send email icon is usually represented by some pictogram or emoji related to mail and sending.",
  "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": "{2ec92193-02c6-4e4d-96b2-19befb0cb07c}"
    }
  }
}