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: Ibea33ed30aca616e8205de69dac0580c82dcc2ed