Add path_id to SerializedPacket. No functional change.

net/quic/quic_sent_packet_manager_test.cc

Index: net/quic/quic_sent_packet_manager_test.cc
diff --git a/net/quic/quic_sent_packet_manager_test.cc b/net/quic/quic_sent_packet_manager_test.cc
index 40adefaaef14df37ea95717400743fe3c88f5a26..da77e48e3aac5a9140b3a98f8d01b9308bff19a9 100644
--- a/net/quic/quic_sent_packet_manager_test.cc
+++ b/net/quic/quic_sent_packet_manager_test.cc
@@ -189,14 +189,16 @@ class QuicSentPacketManagerTest : public ::testing::TestWithParam<bool> {
       frames->AddFrame(
           QuicFrame(new QuicStreamFrame(kStreamId, false, 0, StringPiece())));
     }
-    return SerializedPacket(packet_number, PACKET_6BYTE_PACKET_NUMBER,
-                            packets_.back(), 0u, frames, false, false);
+    return SerializedPacket(kDefaultPathId, packet_number,
+                            PACKET_6BYTE_PACKET_NUMBER, packets_.back(), 0u,
+                            frames, false, false);
   }
 
   SerializedPacket CreateFecPacket(QuicPacketNumber packet_number) {
     packets_.push_back(new QuicEncryptedPacket(nullptr, kDefaultLength));
-    SerializedPacket serialized(packet_number, PACKET_6BYTE_PACKET_NUMBER,
-                                packets_.back(), 0u, nullptr, false, false);
+    SerializedPacket serialized(kDefaultPathId, packet_number,
+                                PACKET_6BYTE_PACKET_NUMBER, packets_.back(), 0u,
+                                nullptr, false, false);
     serialized.is_fec_packet = true;
     return serialized;
   }