Examine source code of Text Character Difference

{
  "manifest_version": 2,
  "name": "Text Character Difference Panel",
  "version": "1.0.0",
  "description": "Compare two texts and count character differences.",
  "browser_action": {
    "default_title": "Char Diff",
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "text-char-diff-0770208c-791d-424c-b633-348e4895f30c@example.com",
      "strict_min_version": "58.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}