Examine source code of Google TTS Reader

{
  "manifest_version": 2,
  "name": "Google TTS Reader",
  "version": "1.0",
  "description": "Read selected text aloud using Google TTS",
  "permissions": [
    "activeTab",
    "tabs"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{2ba4590a-e59c-49cc-b7d2-5cfa71a9df8e}",
      "strict_min_version": "114.0"
    }
  },
  "icons": {
    "64": "icon64.png",
    "128": "icon128.png"
  },
  "browser_action": {
    "default_title": "Google TTS Reader",
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ]
}