deprecate FLAGS_quic_bugfix_fhol_writev_fin_only_v2.

net/quic/core/quic_spdy_session.cc

Index: net/quic/core/quic_spdy_session.cc
diff --git a/net/quic/core/quic_spdy_session.cc b/net/quic/core/quic_spdy_session.cc
index b2bb42ffca2a7efdfb03bc0c757f530cc05e6fe8..99af1244ea6e2a40fe41e0f040282821f975a43c 100644
--- a/net/quic/core/quic_spdy_session.cc
+++ b/net/quic/core/quic_spdy_session.cc
@@ -121,24 +121,15 @@ void QuicSpdySession::OnConfigNegotiated() {
   if (FLAGS_quic_enable_force_hol_blocking && version > QUIC_VERSION_35 &&
       config()->ForceHolBlocking(perspective())) {
     force_hol_blocking_ = true;
-    if (!FLAGS_quic_bugfix_fhol_writev_fin_only_v2) {
-      // Autotuning makes sure that the headers stream flow control does
-      // not get in the way, and normal stream and connection level flow
-      // control are active anyway. This is really only for the client
-      // side (and mainly there just in tests and toys), where
-      // autotuning and/or large buffers are not enabled by default.
-      headers_stream_->flow_controller()->set_auto_tune_receive_window(true);
-    } else {
-      // Since all streams are tunneled through the headers stream, it
-      // is important that headers stream never flow control blocks.
-      // Otherwise, busy-loop behaviour can ensue where data streams
-      // data try repeatedly to write data not realizing that the
-      // tunnel through the headers stream is blocked.
-      headers_stream_->flow_controller()->UpdateReceiveWindowSize(
-          kStreamReceiveWindowLimit);
-      headers_stream_->flow_controller()->UpdateSendWindowOffset(
-          kStreamReceiveWindowLimit);
-    }
+    // Since all streams are tunneled through the headers stream, it
+    // is important that headers stream never flow control blocks.
+    // Otherwise, busy-loop behaviour can ensue where data streams
+    // data try repeatedly to write data not realizing that the
+    // tunnel through the headers stream is blocked.
+    headers_stream_->flow_controller()->UpdateReceiveWindowSize(
+        kStreamReceiveWindowLimit);
+    headers_stream_->flow_controller()->UpdateSendWindowOffset(
+        kStreamReceiveWindowLimit);
   }
 
   if (version > QUIC_VERSION_34) {