Merge "Make MockVpn more realistic and easier to use." am: e191d8d958 am: b1296e900d am: 82f6a11a45

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/1501814

Change-Id: I949afe9dfa706ecce66f3b80a7f3e330dcc49413