Examine source code of ProtonMail Launcher

{
  "manifest_version": 3,
  "name": "ProtonMail Launcher",
  "version": "2.0",
  "description": "Open or switch to ProtonMail from the toolbar.",
  "browser_specific_settings": {
    "gecko": {
      "id": "{b9e14cae-1155-449c-9ab1-dcb3728bcc9e}",
      "strict_min_version": "115.0"
    }
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "action": {
    "default_icon": "icon128.png",
    "default_title": "Open ProtonMail"
  },
  "icons": {
    "128": "icon128.png"
  },
  "commands": {
    "open-protonmail": {
      "description": "Open or switch to ProtonMail"
    }
  },
  "permissions": [
    "contextMenus"
  ],
  "optional_host_permissions": [
    "https://mail.proton.me/*"
  ]
}