Add TcpKeepalivePacketData to SystemApi am: 11511b31f6 am: 349ba03274 am: 7240fd9ea1

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/1494038

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I1aa9deefefcaf75959463e8a8a87bfeefb98f0ee
tree: 0303a09758c8339ce2f04ef9a916b8754ac269e0
  1. core/
  2. services/
  3. tests/
  4. OWNERS