Examine source code of Hydrator

{
  "manifest_version": 2,
  "name": "Hydrator",
  "description": "A browser addon to remind you to drink water frequently while you enjoy your sweet time on your computer.",
  "version": "3.0",
  "icons": {
    "48": "icons/icon_48.png",
    "96": "icons/icon_96.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_icon": "icons/icon_96.png",
    "default_title": "Set timegap",
    "default_popup": "popup/popup.html"
  },
  "permissions": [
    "notifications",
    "alarms"
  ]
}