Merge "Move shared methods and constants from Proxy to shared lib" am: 933b49f9b1 am: e532759305 am: 724a302b7e

Original change: https://android-review.googlesource.com/c/platform/frameworks/libs/net/+/1576988

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I57bffe32c53d194b75b8309626e9c0331c25e4d5