Examine source code of Website Time Limiter

{
  "manifest_version": 2,
  "name": "Website Time Limiter",
  "version": "1.0",
  "description": "Limit access to addictive sites like Facebook, YouTube.",
  "permissions": [
    "tabs",
    "storage",
    "*://*.facebook.com/*",
    "*://*.youtube.com/*"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "browser_action": {
    "default_popup": "options.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.facebook.com/*",
        "*://*.youtube.com/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "web_accessible_resources": [
    "blocked.html"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{79f3050b-aa00-4c27-93ec-29bd61a6fe9b}"
    }
  }
}