Call setUnderlyingNetwork to complete VCN MOBIKE

This change updates the underlying network for the VCN in order to
ensure full MOBIKE switches are handled.

Bug: 169788130
Test: atest FrameworksVcnTests
Change-Id: Ib439bde4217beeb28f425c08ed9f3376dfe0033c

services/core/java/com/android/server/vcn/VcnGatewayConnection.java

@@ -1478,7 +1478,7 @@ public class VcnGatewayConnection extends StateMachine {
                 @NonNull IpSecTransform transform,
                 int direction) {
             try {
-                // TODO(b/180163196): Set underlying network of tunnel interface
+                tunnelIface.setUnderlyingNetwork(underlyingNetwork);
 
                 // Transforms do not need to be persisted; the IkeSession will keep them alive
                 mIpSecManager.applyTunnelModeTransform(tunnelIface, direction, transform);

tests/vcn/java/com/android/server/vcn/VcnGatewayConnectionConnectedStateTest.java

@@ -36,6 +36,7 @@ import static org.mockito.Matchers.eq;
 import static org.mockito.Mockito.doReturn;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.times;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.verifyNoMoreInteractions;
 
@@ -143,11 +144,18 @@ public class VcnGatewayConnectionConnectedStateTest extends VcnGatewayConnection
                 .onIpSecTransformsMigrated(makeDummyIpSecTransform(), makeDummyIpSecTransform());
         mTestLooper.dispatchAll();
 
+        verify(mIpSecSvc, times(2))
+                .setNetworkForTunnelInterface(
+                        eq(TEST_IPSEC_TUNNEL_RESOURCE_ID),
+                        eq(TEST_UNDERLYING_NETWORK_RECORD_1.network),
+                        any());
+
         for (int direction : new int[] {DIRECTION_IN, DIRECTION_OUT}) {
             verify(mIpSecSvc)
                     .applyTunnelModeTransform(
                             eq(TEST_IPSEC_TUNNEL_RESOURCE_ID), eq(direction), anyInt(), any());
         }
+
         assertEquals(mGatewayConnection.mConnectedState, mGatewayConnection.getCurrentState());
     }