Examine source code of Share icon

{
  "manifest_version": 2,
  "name": "Share icon",
  "version": "1.0",
  "description": "Share icons are commonly used in applications, websites or software to indicate the functionality of sharing content (such as articles, photos, videos, links...) to other platforms or other users.",
  "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": "{666106d2-a67f-43cd-afe7-efad55622678}"
    }
  }
}