Examine source code of Focus Blocker

{
  "manifest_version": 2,
  "name": "Focus Blocker",
  "description": "Blocks user‑defined websites and displays the user’s goal(s).",
  "version": "1.0",
  "permissions": [
    "storage",
    "tabs",
    "http://*/*",
    "https://*/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "data_collection_permissions": {
        "required": [
          "locationInfo"
        ],
        "optional": [
          "technicalAndInteraction"
        ]
      },
      "id": "{a1f0d74a-4b2b-443a-a6a6-105e2cb0d252}"
    }
  },
  "browser_action": {
    "default_title": "Firefox Focus Blocker"
  },
  "options_page": "options.html",
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "web_accessible_resources": [
    "blocked.html"
  ]
}