Examine source code of String Case Tool

{
  "manifest_version": 2,
  "name": "String Case Tool",
  "version": "1.0.0",
  "description": "Convert selected text to UPPER, lower, Title, camelCase, snake_case, kebab-case, PascalCase, and sentence case.",
  "browser_specific_settings": {
    "gecko": {
      "id": "{072f3271-58a4-4cb2-ad03-4dc8213974be}",
      "strict_min_version": "96.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "browser_action": {
    "default_icon": {
      "16": "icon16.png",
      "32": "icon32.png",
      "48": "icon48.png",
      "96": "icon96.png",
      "128": "icon128.png"
    },
    "default_title": "String Case Tool",
    "default_popup": "popup.html"
  },
  "icons": {
    "16": "icon16.png",
    "32": "icon32.png",
    "48": "icon48.png",
    "96": "icon96.png",
    "128": "icon128.png"
  },
  "permissions": [
    "tabs",
    "activeTab",
    "contextMenus",
    "clipboardWrite"
  ],
  "content_scripts": [
    {
      "matches": [
        "http://*/*",
        "https://*/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ]
}