Add QUIC_EXPORT_PRIVATE to prepare for presubmit

A subsequent CL (cl/276207410) will add a presubmit to mitigate QUICHE merge issues, this CL gets our code-base to a state of compliance with that presubmit. These haven't caused issues in Chromium if they were only used in the same build unit, but it's worth it to have a consistent use across the codebase to make sure everything works in Chromium.

gfe-relnote: no behavior change, QUIC_EXPORT_PRIVATE is a no-op in google3
PiperOrigin-RevId: 276276729
Change-Id: I67ab8c9df92d24d0006de7084ca563153f0bf07f
diff --git a/quic/core/quic_dispatcher.h b/quic/core/quic_dispatcher.h
index abcd4f2..528d6cf 100644
--- a/quic/core/quic_dispatcher.h
+++ b/quic/core/quic_dispatcher.h
@@ -34,9 +34,10 @@
 class QuicConfig;
 class QuicCryptoServerConfig;
 
-class QuicDispatcher : public QuicTimeWaitListManager::Visitor,
-                       public ProcessPacketInterface,
-                       public QuicBufferedPacketStore::VisitorInterface {
+class QUIC_EXPORT_PRIVATE QuicDispatcher
+    : public QuicTimeWaitListManager::Visitor,
+      public ProcessPacketInterface,
+      public QuicBufferedPacketStore::VisitorInterface {
  public:
   // Ideally we'd have a linked_hash_set: the  boolean is unused.
   typedef QuicLinkedHashMap<QuicBlockedWriterInterface*, bool> WriteBlockedList;