Add work-around for unused private fields in quic/masque

This will allow us to remove `-Wno-unused-private-field` [1] from the Chrome build of Quiche.

[1] https://source.chromium.org/chromium/chromium/src/+/main:net/third_party/quiche/BUILD.gn;l=38;drc=c0a300abd30958ef38c80bf3826a2f7a644f24da

PiperOrigin-RevId: 611580795
diff --git a/quiche/quic/masque/masque_client_session.cc b/quiche/quic/masque/masque_client_session.cc
index 7e5dfdd..4869d13 100644
--- a/quiche/quic/masque/masque_client_session.cc
+++ b/quiche/quic/masque/masque_client_session.cc
@@ -68,7 +68,12 @@
                             crypto_config),
       masque_mode_(masque_mode),
       uri_template_(uri_template),
-      owner_(owner) {}
+      owner_(owner) {
+  // We don't currently use `masque_mode_` but will in the future. To silence
+  // clang's `-Wunused-private-field` warning for this when building QUICHE for
+  // Chrome, add a use of it here.
+  (void)masque_mode_;
+}
 
 void MasqueClientSession::OnMessageAcked(QuicMessageId message_id,
                                          QuicTime /*receive_timestamp*/) {
diff --git a/quiche/quic/masque/masque_server_backend.cc b/quiche/quic/masque/masque_server_backend.cc
index 9b75bcd..f4ff2e0 100644
--- a/quiche/quic/masque/masque_server_backend.cc
+++ b/quiche/quic/masque/masque_server_backend.cc
@@ -28,10 +28,10 @@
 
 namespace quic {
 
-MasqueServerBackend::MasqueServerBackend(MasqueMode masque_mode,
+MasqueServerBackend::MasqueServerBackend(MasqueMode /*masque_mode*/,
                                          const std::string& server_authority,
                                          const std::string& cache_directory)
-    : masque_mode_(masque_mode), server_authority_(server_authority) {
+    : server_authority_(server_authority) {
   // Start with client IP 10.1.1.2.
   connect_ip_next_client_ip_[0] = 10;
   connect_ip_next_client_ip_[1] = 1;
@@ -41,6 +41,11 @@
   if (!cache_directory.empty()) {
     QuicMemoryCacheBackend::InitializeBackend(cache_directory);
   }
+
+  // We don't currently use `masque_mode_` but will in the future. To silence
+  // clang's `-Wunused-private-field` warning for this when building QUICHE for
+  // Chrome, add a use of it here.
+  (void)masque_mode_;
 }
 
 bool MasqueServerBackend::MaybeHandleMasqueRequest(
diff --git a/quiche/quic/masque/masque_server_session.cc b/quiche/quic/masque/masque_server_session.cc
index 6a88ae3..82b9a4d 100644
--- a/quiche/quic/masque/masque_server_session.cc
+++ b/quiche/quic/masque/masque_server_session.cc
@@ -145,6 +145,11 @@
 
   masque_server_backend_->RegisterBackendClient(connection_id(), this);
   QUICHE_DCHECK_NE(event_loop_, nullptr);
+
+  // We don't currently use `masque_mode_` but will in the future. To silence
+  // clang's `-Wunused-private-field` warning for this when building QUICHE for
+  // Chrome, add a use of it here.
+  (void)masque_mode_;
 }
 
 void MasqueServerSession::OnMessageAcked(QuicMessageId message_id,
diff --git a/quiche/quic/masque/masque_server_session.h b/quiche/quic/masque/masque_server_session.h
index b33f7ff..c7659f2 100644
--- a/quiche/quic/masque/masque_server_session.h
+++ b/quiche/quic/masque/masque_server_session.h
@@ -214,7 +214,6 @@
   std::list<ConnectUdpServerState> connect_udp_server_states_;
   std::list<ConnectIpServerState> connect_ip_server_states_;
   std::list<ConnectEthernetServerState> connect_ethernet_server_states_;
-  bool masque_initialized_ = false;
 };
 
 }  // namespace quic