Examine source code of Quick cart icon

{
  "manifest_version": 2,
  "name": "Quick cart icon",
  "version": "1.0",
  "description": "The quick shopping cart icon is used to quickly access the list of selected products to buy, a familiar icon in e-commerce applications and sales 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": "{501efb33-bba3-446b-baee-b241cc25c142}"
    }
  }
}