Remove unused ENDPOINT macro from QuicSpdyStream. No behavior change.

net/quic/quic_spdy_stream.cc

Index: net/quic/quic_spdy_stream.cc
diff --git a/net/quic/quic_spdy_stream.cc b/net/quic/quic_spdy_stream.cc
index a194ef54fe14f69405b14c99ab5d4160ff2a67ce..374405bcbb8e60b757410ba6fa62af3d5d752755 100644
--- a/net/quic/quic_spdy_stream.cc
+++ b/net/quic/quic_spdy_stream.cc
@@ -14,10 +14,6 @@ using std::min;
 
 namespace net {
 
-#define ENDPOINT                                                               \
-  (session()->perspective() == Perspective::IS_SERVER ? "Server: " : "Client:" \
-                                                                     " ")
-
 namespace {
 
 // This is somewhat arbitrary.  It's possible, but unlikely, we will either fail