This service can back up and restore the following:
When auto backup is enabled, the Android Backup Service periodically backs up your phone to a private folder in Google Drive. Auto backup occurs every 24 hours when the phone is idle, charging, and connected to a Wi-Fi network.
Backup data will not count towards your Google Drive storage quota. Large files or files that app developers have chosen to exclude from the service will not be backed up.
This allows an app's data and settings saved through the Android Backup Service to be restored when you reinstall the app on HTC One A9.