ARCore is distributed in the form of an external APK that needs to be installed on the device so the ARCore SDK can make use of it (it is an Android service). The Chromium ARCore integration should check if the APK is present and if the version of ARCore Chromium supports is the correct one compared to the installed one. If these preconditions do not apply, Chromium should request the installation/update of the ARCore APK to the Google Play Store.
 

In order to make the ARCore library smaller in size the ARCore APK handling code has been stripped out from the ARCore SDK that we are using inside Chromium. The chromium code make a subset of the same checks but

1) Chromium will have to maintain code that should not be Chromium's responsibility.
2) Some checks are not being done at the moment like verifying if the device is ARCore enabled or not.

Need to find a way to be able to use the original code from ARCore to perform all these checks. Ian Vollick suggested maybe downloading the ARCore SDK on demand using some Chrome feature.