Merge "Add keepalive related methods and fields to system APIs" am: 434bc5adf4 am: 57e9fd7e5a

Change-Id: Ie4cd12bb96a42f414d7026828e72eea16f4bd073
tree: b3e931f5d4444dc830bd1c752f8f3d9ead3d21cc
  1. core/
  2. services/
  3. tests/