Factorize custom asserts.

Also a few utilities that were in the way, and some opportunistic
cleanups.

Test: FrameworksNetTest NetworkStackTest
Change-Id: I385070e2044fd967cb18f1ffea9a86a4627b742e

tests/net/java/android/net/TcpKeepalivePacketDataTest.java

@@ -16,14 +16,14 @@
 
 package android.net;
 
+import static com.android.testutils.ParcelUtilsKt.assertParcelingIsLossless;
+
 import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.fail;
 
 import android.net.SocketKeepalive.InvalidPacketException;
 
-import com.android.internal.util.TestUtils;
-
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -79,7 +79,7 @@ public final class TcpKeepalivePacketDataTest {
         assertEquals(testInfo.tos, resultData.ipTos);
         assertEquals(testInfo.ttl, resultData.ipTtl);
 
-        TestUtils.assertParcelingIsLossless(resultData);
+        assertParcelingIsLossless(resultData);
 
         final byte[] packet = resultData.getPacket();
         // IP version and IHL