Examine source code of Pronunciation Guide

{
  "manifest_version": 2,
  "name": "Pronunciation Guide",
  "version": "1.0",
  "description": "Highlight a word and get pronunciation guide using a speech API.",
  "permissions": [
    "contextMenus",
    "activeTab",
    "storage"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{a9b54f99-9529-4d7f-9596-1d31a12595c5}"
    }
  }
}