Examine source code of GGSEL Notifier

{
  "manifest_version": 2,
  "name": "GGSEL Notifier",
  "version": "1.3",
  "description": "Sound and visual notifications for new messages on GGSEL seller panel.",
  "browser_specific_settings": {
    "gecko": {
      "id": "{570691b5-d637-4ed1-abd6-c89d1155a13f}",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "permissions": [
    "notifications",
    "tabs",
    "storage",
    "https://seller.ggsel.net/*",
    "https://ggsel.com/*",
    "https://seller.ggsel.com/*"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_title": "GGSEL Notifier",
    "default_icon": "icon.png"
  },
  "options_page": "options.html",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "https://seller.ggsel.net/*messages*",
        "https://seller.ggsel.net/*orders*",
        "https://ggsel.com/seller/*messages*",
        "https://ggsel.com/seller/*orders*",
        "https://seller.ggsel.com/*messages*",
        "https://seller.ggsel.com/*orders*"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "web_accessible_resources": [
    "notif.mp3",
    "order.mp3"
  ],
  "icons": {
    "48": "icon.png",
    "96": "icon-96.png"
  }
}