Examine source code of Text Case Converter

{
  "manifest_version": 2,
  "name": "Text Case Converter",
  "version": "1.0",
  "description": "Convert selected text to uppercase, lowercase, or capitalized.",
  "permissions": [
    "contextMenus",
    "activeTab",
    "clipboardWrite"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "textcase@example.com",
      "strict_min_version": "58.0"
    }
  }
}