Add TcpKeepalivePacketData to SystemApi am: 103ec4aa8d am: a232c68028

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

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: Ic764adda49e414e6ed34a101fd83c3fc62f5734c