Examine source code of Simple Countdown Timer

{
  "manifest_version": 2,
  "name": "Simple Countdown Timer",
  "version": "1.0",
  "description": "Simple Countdown Timer. This utility allows users to set a countdown time and display the remaining time.",
  "permissions": [],
  "browser_action": {
    "default_popup": "game.html",
    "default_icon": {
      "128": "images/coun-logo.png"
    }
  },
  "icons": {
    "128": "images/coun-logo.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{cf35a07e-fc85-4fa1-8e09-ae60b47e741e}"
    }
  }
}