Add a new method to QuicSpdySession

net/quic/quic_spdy_session.h

Index: net/quic/quic_spdy_session.h
diff --git a/net/quic/quic_spdy_session.h b/net/quic/quic_spdy_session.h
index 77ebe2e48a6a71bf82946b5b9c94a3c0f3f51443..6f7b4a01e52b762321ba2b7fa4e049b4b90b8dfd 100644
--- a/net/quic/quic_spdy_session.h
+++ b/net/quic/quic_spdy_session.h
@@ -51,6 +51,10 @@ class NET_EXPORT_PRIVATE QuicSpdySession : public QuicSession {
 
   QuicHeadersStream* headers_stream() { return headers_stream_.get(); }
 
+  // Called when Head of Line Blocking happens in the headers stream.
+  // |delta| indicates how long that piece of data has been blocked.
+  virtual void OnHeadersHeadOfLineBlocking(QuicTime::Delta delta);
+
  protected:
   // Override CreateIncomingDynamicStream() and CreateOutgoingDynamicStream()
   // with QuicSpdyStream return type to make sure that all data streams are