Examine source code of Icon Click Tracker

{
  "manifest_version": 2,
  "name": "Click Counter Badge",
  "version": "1.0",
  "description": "Counts how many times the extension icon is clicked and shows it as a badge.",
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_title": "Click Counter Badge",
    "default_icon": "icon.png"
  },
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{fd6d5cfa-216a-4924-828a-1723880e454a}"
    }
  }
}