Examine source code of Energy Usage Estimator

{
  "manifest_version": 3,
  "name": "__MSG_extensionName__",
  "version": "1.0",
  "description": "__MSG_extensionDescription__",
  "permissions": [
    "storage",
    "activeTab"
  ],
  "action": {
    "default_popup": "popup.html",
    "default_icon": {
      "48": "icons/icon48.png"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "energy-usage-estimator@example.com"
    }
  },
  "icons": {
    "48": "icons/icon48.png"
  }
}