Examine source code of rofi tab switcher

{
  "manifest_version": 2,
  "name": "rofi tab switcher",
  "version": "1.1",
  "description": "Switch between tabs using rofi.",
  "commands": {
    "switch-tab": {
      "suggested_key": {
        "default": "Ctrl+Comma",
        "linux": "Ctrl+Comma"
      },
      "description": "Switch tab"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "nativeMessaging",
    "tabs",
    "activeTab"
  ],
  "applications": {
    "gecko": {
      "id": "@rofi.tab.switcher"
    }
  }
}