https://www.theverge.com/circuitbreaker/2017/10/30/16569444/android-8-1-text-messages-chromebook-google

We’ve heard rumors about receiving and sending text messages on the Chromebook before, but that function has now been discovered in the developer preview for Android 8.1, as spotted by ArsTechnica and 9to5Google.

Called SMS Connect, the feature allows users to send and receive text messages from their phone using the device's carrier number on the Chromebook. Users will also be alerted to new text messages through notifications. The feature was discovered in an APK called "SMSConnectPrebuilt," which is launched through an activity browser where a setup screen for SMS Connect opens.