Add a systemapi constructor for NetworkAgent am: 1a8802b0e1 am: de6d7d5a25

Change-Id: I091a6c7d8e92c22ca9393b5c974fcda5356d4102
tree: 3917d49661d1ce2df12e81907e6925d3bcf97702
  1. core/
  2. services/
  3. tests/