Examine source code of YouTube Mute Timer

{
  "manifest_version": 2,
  "name": "YouTube Mute Timer",
  "version": "1.0.0",
  "description": "YouTubeでタイマーボタンがクリックされたら一時的にミュートにします。",
  "icons": {
    "16": "images/icon16.png",
    "48": "images/icon48.png",
    "128": "images/icon128.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_title": "YouTube Mute Timer"
  },
  "content_scripts": [
    {
      "matches": [
        "*://www.youtube.com/*"
      ],
      "css": [
        "content.css"
      ],
      "js": [
        "jquery.min.js",
        "content.js"
      ]
    }
  ],
  "permissions": [
    "*://www.youtube.com/*",
    "storage"
  ],
  "options_ui": {
    "page": "options.html",
    "open_in_tab": true
  },
  "web_accessible_resources": [
    "inject.js",
    "images/icon24.png",
    "images/icon24-run.png"
  ]
}