Adding details to most quic connection close calls.

net/tools/quic/quic_dispatcher.cc

Index: net/tools/quic/quic_dispatcher.cc
diff --git a/net/tools/quic/quic_dispatcher.cc b/net/tools/quic/quic_dispatcher.cc
index bb4bd88ae9dc69296b3c64d7f4ee028efb9d111d..b1af414d89fe93328780668b965bed95b707096a 100644
--- a/net/tools/quic/quic_dispatcher.cc
+++ b/net/tools/quic/quic_dispatcher.cc
@@ -390,7 +390,8 @@ bool QuicDispatcher::HasPendingWrites() const {
 void QuicDispatcher::Shutdown() {
   while (!session_map_.empty()) {
     QuicServerSession* session = session_map_.begin()->second;
-    session->connection()->SendConnectionClose(QUIC_PEER_GOING_AWAY);
+    session->connection()->SendConnectionCloseWithDetails(
+        QUIC_PEER_GOING_AWAY, "Server shutdown imminent");
     // Validate that the session removes itself from the session map on close.
     DCHECK(session_map_.empty() || session_map_.begin()->second != session);
   }