Examine source code of YouTube Audio Manager

{
  "manifest_version": 2,
  "name": "YouTube Audio Manager",
  "version": "1.0.3",
  "description": "YouTubeの音量をチャンネル単位で管理・記憶するブラウザ拡張機能",
  "permissions": [
    "storage",
    "activeTab",
    "https://www.youtube.com/*"
  ],
  "background": {
    "scripts": [
      "shared/constants.js",
      "shared/validator.js",
      "shared/storage.js",
      "background/background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "https://www.youtube.com/*"
      ],
      "js": [
        "shared/constants.js",
        "shared/validator.js",
        "shared/storage.js",
        "content/channel-detector.js",
        "content/audio-manager.js",
        "content/toolbar-buttons.js",
        "content/volume-dialog.js",
        "content/content.js"
      ],
      "css": [
        "styles/toolbar-buttons.css",
        "styles/volume-dialog.css"
      ],
      "run_at": "document_idle"
    }
  ],
  "browser_action": {
    "default_popup": "popup/popup.html",
    "default_icon": {
      "16": "icons/icon-16.png",
      "48": "icons/icon-48.png",
      "128": "icons/icon-128.png"
    }
  },
  "options_ui": {
    "page": "options/options.html",
    "open_in_tab": true
  },
  "icons": {
    "16": "icons/icon-16.png",
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "content_security_policy": "script-src 'self'; object-src 'self'",
  "browser_specific_settings": {
    "gecko": {
      "id": "youtube-audio-manager@example.com",
      "strict_min_version": "142.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}