Examine source code of Focus Timer Badge

{
  "manifest_version": 2,
  "name": "Focus Timer Badge",
  "version": "1.0",
  "description": "A countdown timer on the extension icon for Pomodoro technique.",
  "permissions": [
    "storage"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_title": "Focus Timer",
    "default_icon": "icon.png"
  },
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{7219d134-ba1f-46e9-9aed-41ed538dd14e}"
    }
  }
}