Add TcpKeepalivePacketData to SystemApi am: 11511b31f6

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

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: Ibe3df65b4e12ecda5d95737f3b1ea18dabc2461d
tree: 90790175763eb87e20bc1ddd48fad38ab9cabc1d
  1. core/
  2. services/
  3. tests/
  4. OWNERS