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_packet_reader.h b/quic/core/quic_packet_reader.h
index 1826ef3..1e644aa 100644
--- a/quic/core/quic_packet_reader.h
+++ b/quic/core/quic_packet_reader.h
@@ -25,7 +25,7 @@
 const int kNumPacketsPerReadMmsgCall = 16;
 #endif
 
-class QuicPacketReader {
+class QUIC_EXPORT_PRIVATE QuicPacketReader {
  public:
   QuicPacketReader();
   QuicPacketReader(const QuicPacketReader&) = delete;
@@ -70,7 +70,7 @@
   // from exceeding maximum allowed frame size.
   // packets_ and mmsg_hdr_ are used to supply cbuf and buf to the recvmmsg
   // call.
-  struct PacketData {
+  struct QUIC_EXPORT_PRIVATE PacketData {
     iovec iov;
     // raw_address is used for address information provided by the recvmmsg
     // call on the packets.