Merge "Add constants of VpnManager events" am: 3cca242ec3 am: b4c82c6f3a am: af3813a332 am: b7260a552a

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/1899036

Change-Id: I88680d5e269e912099919f0693d172e2317942cf