Examine source code of SmartAlert

{
  "manifest_version": 2,
  "name": "SmartAlert",
  "version": "1.0",
  "description": "Phát âm báo khác nhau cho Gmail, Slack, Messenger.",
  "permissions": [
    "tabs"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "*://mail.google.com/*",
        "*://*.slack.com/*",
        "*://*.messenger.com/*"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "smartalert@amo",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}