Examine source code of Talking Alarm Clock

{
  "name": "Talking Alarm Clock",
  "version": "1.3",
  "description": "A clock with two configurable alarms that will play a sound and speak a phrase of your choice.",
  "permissions": [
    "background",
    "tts"
  ],
  "background": {
    "scripts": [
      "common.js",
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": "clock-19.png",
    "default_title": "Talking Alarm Clock",
    "default_popup": "popup.html"
  },
  "icons": {
    "16": "clock-16.png",
    "48": "clock-48.png",
    "128": "clock-128.png",
    "256": "clock-256.png"
  },
  "manifest_version": 2,
  "browser_specific_settings": {
    "gecko": {
      "id": "{8568c573-4393-4f61-9c80-a711bf34e95f}"
    }
  }
}