Examine source code of Focus Blocker

{
  "manifest_version": 2,
  "name": "Focus Blocker",
  "version": "1.0.0",
  "description": "Block distracting sites during focus time. Toggle quickly, add current site, and set a focus timer from the popup.",
  "permissions": [
    "storage",
    "tabs",
    "alarms",
    "webRequest",
    "webRequestBlocking",
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_title": "Focus Blocker",
    "default_popup": "popup.html",
    "default_icon": {
      "48": "icons/icon48.png",
      "128": "icons/icon128.png"
    }
  },
  "icons": {
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "web_accessible_resources": [
    "blocked.html",
    "blocked.js"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "focus-blocker@example.com",
      "strict_min_version": "91.0"
    }
  }
}