Examine source code of Speech Synthesis

{
  "manifest_version": 2,
  "name": "Text to Speech",
  "version": "1.0",
  "description": "Convert selected text to speech in multiple languages.",
  "permissions": [
    "activeTab",
    "contextMenus",
    "tts"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "icons": {
    "48": "icon.png"
  },
  "browser_action": {
    "default_icon": "icon.png",
    "default_title": "Text to Speech"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{0e5f2f17-ab4f-4d12-b177-8606c42e9312}"
    }
  }
}