Examine source code of Text Line Length Analyzer

{
  "manifest_version": 2,
  "name": "Text Line Length Analyzer Addon",
  "version": "1.0.0",
  "description": "Show the length of each line in text.",
  "browser_action": {
    "default_title": "Line Length",
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "line-length-analyzer-3d1851f8-8e15-437d-aa55-d4bb2cd5d10c@example.com",
      "strict_min_version": "58.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}