Remove dependency on headers stream from QuicSession.

net/quic/quic_data_stream.cc

Index: net/quic/quic_data_stream.cc
diff --git a/net/quic/quic_data_stream.cc b/net/quic/quic_data_stream.cc
index 37013279fb8550debcb2c03dc10a8ce8c2c6e0eb..56622de36b4bc3ac111b6341666b649208e20ff4 100644
--- a/net/quic/quic_data_stream.cc
+++ b/net/quic/quic_data_stream.cc
@@ -5,7 +5,7 @@
 #include "net/quic/quic_data_stream.h"
 
 #include "base/logging.h"
-#include "net/quic/quic_session.h"
+#include "net/quic/quic_spdy_session.h"
 #include "net/quic/quic_utils.h"
 #include "net/quic/quic_write_blocked_list.h"
 
@@ -28,8 +28,9 @@ QuicPriority kDefaultPriority = 3;
 
 }  // namespace
 
-QuicDataStream::QuicDataStream(QuicStreamId id, QuicSession* session)
-    : ReliableQuicStream(id, session),
+QuicDataStream::QuicDataStream(QuicStreamId id, QuicSpdySession* spdy_session)
+    : ReliableQuicStream(id, spdy_session),
+      spdy_session_(spdy_session),
       visitor_(nullptr),
       headers_decompressed_(false),
       priority_(kDefaultPriority) {
@@ -46,7 +47,7 @@ size_t QuicDataStream::WriteHeaders(
     const SpdyHeaderBlock& header_block,
     bool fin,
     QuicAckNotifier::DelegateInterface* ack_notifier_delegate) {
-  size_t bytes_written = session()->WriteHeaders(
+  size_t bytes_written = spdy_session_->WriteHeaders(
       id(), header_block, fin, priority_, ack_notifier_delegate);
   if (fin) {
     // TODO(rch): Add test to ensure fin_sent_ is set whenever a fin is sent.