Restrict app data on metered networks.

This separates the definition of "metered network" and "network with
limit."  For now, all mobile networks are considered metered.

Bug: 5571454
Change-Id: I394cd385bd33add75e53bfc9cf2fefd06a00208a

services/tests/servicestests/src/com/android/server/NetworkStatsServiceTest.java

@@ -802,6 +802,8 @@ public class NetworkStatsServiceTest extends AndroidTestCase {
 
         mNetManager.setGlobalAlert(anyLong());
         expectLastCall().atLeastOnce();
+
+        expect(mNetManager.isBandwidthControlEnabled()).andReturn(true).atLeastOnce();
     }
 
     private void expectNetworkState(NetworkState... state) throws Exception {