Examine source code of Browsing Fast and Slow

{
  "manifest_version": 2,
  "name": "Browsing Fast and Slow",
  "version": "1.2",
  "description": "Block websites with delayed access approval",
  "icons": {
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png"
  },
  "permissions": [
    "storage",
    "webRequest",
    "webRequestBlocking",
    "tabs",
    "<all_urls>"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "@browsing-fast-and-slow",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "browser_action": {
    "default_icon": "icons/icon-48.png",
    "default_title": "Browsing Fast & Slow",
    "default_popup": "popup/popup.html"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": true
  },
  "web_accessible_resources": [
    "blocked.html",
    "approval.html",
    "waiting.html"
  ]
}