Examine source code of Barcode scanner emulator

{
  "manifest_version": 2,
  "browser_specific_settings": {
    "gecko": {
      "id": "{65a78cb3-8122-4ebe-bc13-c100c8ceaa98}",
      "strict_min_version": "64.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "name": "Barcode scanner emulator",
  "version": "1.1",
  "description": "Emulates the input of a barcode scanner line",
  "permissions": [
    "activeTab"
  ],
  "icons": {
    "48": "icon.svg"
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icon.svg"
  },
  "commands": {
    "_execute_browser_action": {
      "suggested_key": {
        "default": "Ctrl+E",
        "mac": "Ctrl+E"
      },
      "description": "Открыть эмулятор"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ]
}