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

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

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I3bb5b01f8d81c9103c69f1c6ed35749d0a81a3ed