Examine source code of Mute Tab Manager

{
  "manifest_version": 3,
  "name": "Mute Tab Manager",
  "description": "Mute/unmute tabs with proper YouTube support.",
  "version": "1.0.1",
  "icons": {
    "16": "icons/icon-16.png",
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "action": {
    "default_icon": {
      "16": "icons/icon-16.png",
      "48": "icons/icon-48.png",
      "128": "icons/icon-128.png"
    },
    "default_title": "Toggle Mute"
  },
  "commands": {
    "toggle-mute": {
      "description": "Toggle mute for the active tab",
      "suggested_key": {
        "default": "Alt+Shift+M"
      }
    }
  },
  "host_permissions": [
    "*://*.youtube.com/*"
  ],
  "permissions": [
    "activeTab",
    "tabs",
    "contextMenus",
    "storage"
  ],
  "browser_specific_settings": {
    "gecko": {
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      },
      "id": "mute-tab@mynameistito",
      "strict_min_version": "140.0"
    }
  },
  "background": {
    "type": "module",
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.youtube.com/*"
      ],
      "all_frames": true,
      "run_at": "document_idle",
      "js": [
        "content-scripts/youtube.js"
      ]
    }
  ]
}