relnote: Measure HOL blocking in QUIC headers stream. Flag protected by quic_measure_headers_hol_bl…

net/quic/quic_headers_stream.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NET_QUIC_QUIC_HEADERS_STREAM_H_
 #define NET_QUIC_QUIC_HEADERS_STREAM_H_
 
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "net/base/net_export.h"
@@ skipping 57 matching lines @@
   // Returns true if the session is still connected.
   bool IsConnected();
 
   QuicSpdySession* spdy_session_;
 
   // Data about the stream whose headers are being processed.
   QuicStreamId stream_id_;
   bool fin_;
   size_t frame_len_;
 
+  // Helper variable that caches the corresponding feature flag.
+  bool measure_headers_hol_blocking_time_;
+
+  // Timestamps used to measure HOL blocking, these are recorded by
+  // the sequencer approximate to the time of arrival off the wire.
+  // |cur_max_timestamp_| tracks the most recent arrival time of
+  // frames for current (at the headers stream level) processed
+  // stream's headers, and |prev_max_timestamp_| tracks the most
+  // recent arrival time of lower numbered streams.
+  QuicTime cur_max_timestamp_;
+  QuicTime prev_max_timestamp_;
+
   SpdyFramer spdy_framer_;
   scoped_ptr<SpdyFramerVisitor> spdy_framer_visitor_;
 
   DISALLOW_COPY_AND_ASSIGN(QuicHeadersStream);
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUIC_HEADERS_STREAM_H_