Examine source code of Focus Mode Enhanced

{
  "manifest_version": 3,
  "name": "Focus Mode Enhanced",
  "version": "4.43",
  "description": "Enable focus mode on several websites.",
  "icons": {
    "16": "images/icon-16.png",
    "32": "images/icon-32.png",
    "48": "images/icon-48.png",
    "128": "images/icon-128.png"
  },
  "action": {
    "default_icon": {
      "16": "images/icon-16.png",
      "32": "images/icon-32.png",
      "48": "images/icon-48.png",
      "128": "images/icon-128.png"
    }
  },
  "author": "benilda.key@yekneb.com",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{5A6E717C-E0DA-4F85-9832-5AC40EC61147}",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      },
      "strict_min_version": "140.0"
    }
  },
  "commands": {
    "_execute_action": {
      "suggested_key": {
        "default": "Alt+Shift+F"
      },
      "description": "Toggle focus mode"
    }
  },
  "homepage_url": "https://github.com/BenKey/focus-mode-enhanced",
  "permissions": [
    "scripting",
    "activeTab"
  ]
}