Examine source code of YouTube Language Helper

{
  "manifest_version": 2,
  "name": "YouTube Language Helper",
  "version": "1.0",
  "description": "Practice listening to foreign languages on YouTube with slowed playback, bilingual subtitles, and automatic sentence repetition.",
  "permissions": [
    "activeTab",
    "storage"
  ],
  "icons": {
    "48": "icon.png"
  },
  "browser_action": {
    "default_title": "YouTube Language Helper",
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://www.youtube.com/*"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{b21cb83d-270d-4272-a7b6-71d6d0a33344}"
    }
  }
}