Remove member "perspective_" in QuicStream.

It's rarely used in the class and can be replaced by session_->perspective().
Removing it simplifies the stream class.

gfe-relnote: no behavior change. Not protected.
PiperOrigin-RevId: 278974865
Change-Id: I5477d521dd945987c331ec0c960c99bef70ea203
diff --git a/quic/core/quic_stream.cc b/quic/core/quic_stream.cc
index ee9cb7b..e2a57dd 100644
--- a/quic/core/quic_stream.cc
+++ b/quic/core/quic_stream.cc
@@ -22,7 +22,7 @@
 namespace quic {
 
 #define ENDPOINT \
-  (perspective_ == Perspective::IS_SERVER ? "Server: " : "Client: ")
+  (session_->perspective() == Perspective::IS_SERVER ? "Server: " : "Client: ")
 
 namespace {
 
@@ -351,7 +351,6 @@
       fin_received_(fin_received),
       rst_sent_(false),
       rst_received_(false),
-      perspective_(session_->perspective()),
       flow_controller_(std::move(flow_controller)),
       connection_flow_controller_(connection_flow_controller),
       stream_contributes_to_connection_flow_control_(true),
@@ -365,7 +364,7 @@
       type_(VersionHasIetfQuicFrames(session->transport_version()) &&
                     type != CRYPTO
                 ? QuicUtils::GetStreamType(id_,
-                                           perspective_,
+                                           session->perspective(),
                                            session->IsIncomingStream(id_))
                 : type) {
   if (type_ == WRITE_UNIDIRECTIONAL) {