On Android, the ANDROID_ID is constant for a user profile on a device (see discussion here). This does not appear to be the case on ARC, but ARC is very new and hopefully this will change.
It is also worth noting - in regards to device identification with ARC - that the Android serial # is not available on ARC, that WiFi MAC address is not currently available (yes, I've seen people talk about using this for device id), and product model information is not available.
Motivation: I know it is not now recommended, but I think a lot of apps use the ANDROID_ID to identify devices in their server database.
The behavior of ANDROID_ID on Android means that, if a user uninstalls your app and then re-installs it, you would know and could eg. re-sync their data to the device. And if a user installs two apps of your apps, you know they are on the same device (and user profile).
