Reset mNetDataPrefixes when Thread goes down.

Bug: 335762753

Test: atest ThreadNetworkIntegrationTests:android.net.thread.ThreadIntegrationTest#toggleThreadNetwork_routeFromPreviousNetDataIsRemoved

Change-Id: I7fd56dcec32ad2b57338ca8033aaa0a95020304e
diff --git a/thread/service/java/com/android/server/thread/TunInterfaceController.java b/thread/service/java/com/android/server/thread/TunInterfaceController.java
index c3f6ace..b76c1e9 100644
--- a/thread/service/java/com/android/server/thread/TunInterfaceController.java
+++ b/thread/service/java/com/android/server/thread/TunInterfaceController.java
@@ -128,6 +128,10 @@
             for (LinkAddress address : mLinkProperties.getAllLinkAddresses()) {
                 removeAddress(address);
             }
+            for (RouteInfo route : mLinkProperties.getAllRoutes()) {
+                mLinkProperties.removeRoute(route);
+            }
+            mNetDataPrefixes.clear();
         }
         nativeSetInterfaceUp(mIfName, isUp);
     }
diff --git a/thread/tests/integration/src/android/net/thread/ThreadIntegrationTest.java b/thread/tests/integration/src/android/net/thread/ThreadIntegrationTest.java
index 4028014..91ca23e 100644
--- a/thread/tests/integration/src/android/net/thread/ThreadIntegrationTest.java
+++ b/thread/tests/integration/src/android/net/thread/ThreadIntegrationTest.java
@@ -307,6 +307,23 @@
                 .isFalse();
     }
 
+    @Test
+    public void toggleThreadNetwork_routeFromPreviousNetDataIsRemoved() throws Exception {
+        ConnectivityManager cm = mContext.getSystemService(ConnectivityManager.class);
+        mController.joinAndWait(DEFAULT_DATASET);
+        mOtCtl.executeCommand("prefix add " + TEST_NO_SLAAC_PREFIX + " pros med");
+        mOtCtl.executeCommand("netdata register");
+
+        mController.leaveAndWait();
+        mOtCtl.factoryReset();
+        mController.joinAndWait(DEFAULT_DATASET);
+
+        LinkProperties lp = cm.getLinkProperties(getThreadNetwork(CALLBACK_TIMEOUT));
+        assertThat(lp).isNotNull();
+        assertThat(lp.getRoutes().stream().anyMatch(r -> r.matches(TEST_NO_SLAAC_PREFIX_ADDRESS)))
+                .isFalse();
+    }
+
     // TODO (b/323300829): add more tests for integration with linux platform and
     // ConnectivityService