Can be used by a network to indicate when it's congested, meaning that apps should defer network traffic that could be done at a later time. Test: bit FrameworksNetTests:android.net.,com.android.server.net.,com.android.server.connectivity.VpnTest,com.android.server.ConnectivityServiceTest Bug: 64133169 Change-Id: I97664d041920c8d6e3f9fb7c9e8638925b15c30e