Examine source code of Email Checker for Gmail™

{
  "manifest_version": 3,
  "name": "__MSG_appName__",
  "short_name": "__MSG_appShortName__",
  "version": "1.1.1",
  "default_locale": "en",
  "description": "__MSG_appDesc__",
  "browser_specific_settings": {
    "gecko": {
      "id": "email-checker@sergeycommit.github.io",
      "strict_min_version": "128.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "permissions": [
    "alarms",
    "notifications",
    "storage",
    "identity"
  ],
  "optional_host_permissions": [
    "https://mail.google.com/*",
    "https://graph.microsoft.com/*",
    "https://login.microsoftonline.com/*"
  ],
  "background": {
    "scripts": [
      "feed.js",
      "offscreen.js",
      "sw.js"
    ]
  },
  "action": {
    "default_icon": {
      "16": "icons/icon-16.png",
      "48": "icons/icon-48.png",
      "128": "icons/icon-128.png"
    },
    "default_title": "__MSG_appShortName__"
  },
  "sidebar_action": {
    "default_panel": "sidepanel.html",
    "default_title": "__MSG_appShortName__",
    "default_icon": {
      "16": "icons/icon-16.png",
      "48": "icons/icon-48.png"
    }
  },
  "icons": {
    "16": "icons/icon-16.png",
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  }
}