Add checks to ensure the session always keeps number of sockets and readers.

Bug: 1014092
Change-Id: I74f4b64b6cb677f05f8ff84e48734c164bcc6b61
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1900397Reviewed-by: Ryan Hamilton <rch@chromium.org>
Commit-Queue: Ryan Hamilton <rch@chromium.org>
Cr-Commit-Position: refs/heads/master@{#712847}

net/quic/quic_chromium_client_session.cc

@@ -799,6 +799,7 @@ QuicChromiumClientSession::QuicChromiumClientSession(
   packet_readers_.push_back(std::make_unique<QuicChromiumPacketReader>(
       sockets_.back().get(), clock, this, yield_after_packets,
       yield_after_duration, net_log_));
+  CHECK_EQ(packet_readers_.size(), sockets_.size());
   crypto_stream_.reset(
       crypto_client_stream_factory->CreateQuicCryptoClientStream(
           session_key.server_id(), this,
@@ -1750,6 +1751,7 @@ void QuicChromiumClientSession::OnConnectionClosed(
     std::move(callback_).Run(ERR_QUIC_PROTOCOL_ERROR);
   }
 
+  CHECK_EQ(sockets_.size(), packet_readers_.size());
   for (auto& socket : sockets_) {
     socket->Close();
   }
@@ -3070,7 +3072,7 @@ bool QuicChromiumClientSession::MigrateToSocket(
     std::unique_ptr<DatagramClientSocket> socket,
     std::unique_ptr<QuicChromiumPacketReader> reader,
     std::unique_ptr<QuicChromiumPacketWriter> writer) {
-  DCHECK_EQ(sockets_.size(), packet_readers_.size());
+  CHECK_EQ(sockets_.size(), packet_readers_.size());
 
   // TODO(zhongyi): figure out whether we want to limit the number of
   // connection migrations for v2, which includes migration on platform signals,