Add a probability to Alternate-Protocol support.

net/quic/quic_stream_factory.cc

 // Copyright (c) 2012 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.
 
 #include "net/quic/quic_stream_factory.h"
 
 #include <set>
 
 #include "base/cpu.h"
 #include "base/message_loop/message_loop.h"
@@ skipping 921 matching lines @@
   // alternate-protocol state is unknown.
   if (!http_server_properties_->HasAlternateProtocol(server))
     return;
 
   // TODO(rch):  In the special case where the session has received no
   // packets from the peer, we should consider blacklisting this
   // differently so that we still race TCP but we don't consider the
   // session connected until the handshake has been confirmed.
   HistogramBrokenAlternateProtocolLocation(
       BROKEN_ALTERNATE_PROTOCOL_LOCATION_QUIC_STREAM_FACTORY);
-  PortAlternateProtocolPair alternate =
+  AlternateProtocolInfo alternate =
       http_server_properties_->GetAlternateProtocol(server);
   DCHECK_EQ(QUIC, alternate.protocol);
 
   // Since the session was active, there's no longer an
   // HttpStreamFactoryImpl::Job running which can mark it broken, unless the
   // TCP job also fails. So to avoid not using QUIC when we otherwise could,
   // we mark it as broken, and then immediately re-enable it. This leaves
   // QUIC as "recently broken" which means that 0-RTT will be disabled but
   // we'll still race.
   http_server_properties_->SetBrokenAlternateProtocol(server);
   http_server_properties_->ClearAlternateProtocol(server);
   http_server_properties_->SetAlternateProtocol(
-      server, alternate.port, alternate.protocol);
+      server, alternate.port, alternate.protocol, 1);
   DCHECK_EQ(QUIC,
             http_server_properties_->GetAlternateProtocol(server).protocol);
   DCHECK(http_server_properties_->WasAlternateProtocolRecentlyBroken(
       server));
 }
 
 }  // namespace net