Examine source code of youtube timer

{
  "description": "My youtube watching behavior beta: shows how much time have you been watching youtube",
  "manifest_version": 2,
  "name": "youtube_analytics",
  "version": "1.1resigned1",
  "applications": {
    "gecko": {
      "id": "youtube@analytics.com"
    }
  },
  "permissions": [
    "tabs",
    "activeTab",
    "notifications",
    "storage",
    "*://*.youtube.com/*"
  ],
  "background": {
    "scripts": [
      "background_script.js"
    ]
  },
  "options_ui": {
    "page": "notification_options.html",
    "browser_style": true
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.youtube.com/*"
      ],
      "js": [
        "youtube_behavior.js"
      ]
    }
  ]
}