Examine source code of Choosy

{
  "name": "Choosy",
  "manifest_version": 2,
  "version": "2.0.1",
  "description": "Send pages and links to another browser using Choosy (macOS only).",
  "icons": {
    "16": "images/icon16.png",
    "48": "images/icon48.png",
    "128": "images/icon128.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_title": "Open with Choosy",
    "default_icon": {
      "16": "images/icon16.png",
      "19": "images/icon19.png",
      "32": "images/icon32.png",
      "38": "images/icon38.png",
      "64": "images/icon64.png"
    }
  },
  "permissions": [
    "activeTab",
    "contextMenus",
    "nativeMessaging"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "firefox@choosyosx.com"
    }
  }
}