Examine source code of Website Blocker

{
  "manifest_version": 2,
  "name": "Website Blocker",
  "version": "0.1.1",
  "description": "Block distracting websites and increase your productivity",
  "icons": {
    "16": "images/icon-16.png",
    "48": "images/icon-48.png",
    "128": "images/icon-128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{5b0b13d0-2961-4e65-b59b-1cf30e3023bb}",
      "strict_min_version": "42.0"
    }
  },
  "content_scripts": [
    {
      "run_at": "document_start",
      "js": [
        "content.js"
      ],
      "matches": [
        "<all_urls>"
      ]
    }
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_title": "Block website",
    "default_icon": {
      "16": "images/icon-16.png",
      "48": "images/icon-48.png",
      "128": "images/icon-128.png"
    }
  },
  "permissions": [
    "storage",
    "activeTab"
  ]
}