Add a probability to Alternate-Protocol support.

net/http/http_network_session.h

 // 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.
 
 #ifndef NET_HTTP_HTTP_NETWORK_SESSION_H_
 #define NET_HTTP_HTTP_NETWORK_SESSION_H_
 
 #include <set>
 #include <string>
 #include <vector>
@@ skipping 86 matching lines @@
     std::string trusted_spdy_proxy;
     // Controls whether or not ssl is used when in SPDY mode.
     bool force_spdy_over_ssl;
     // Controls whether or not SPDY is used without NPN.
     bool force_spdy_always;
     // URLs to exclude from forced SPDY.
     std::set<HostPortPair> forced_spdy_exclusions;
     // Noe: Using this in the case of NPN for HTTP only results in the browser
     // trying SSL and then falling back to http.
     bool use_alternate_protocols;
+    double alternate_protocol_probability_threshold;
     bool enable_websocket_over_spdy;
 
     bool enable_quic;
     bool enable_quic_port_selection;
     bool enable_quic_pacing;
     bool enable_quic_time_based_loss_detection;
     bool enable_quic_persist_server_info;
     HostPortPair origin_to_force_quic_on;
     QuicClock* quic_clock;  // Will be owned by QuicStreamFactory.
     QuicRandom* quic_random;
@@ skipping 120 matching lines @@
 
   std::vector<std::string> next_protos_;
   bool enabled_protocols_[NUM_VALID_ALTERNATE_PROTOCOLS];
 
   Params params_;
 };
 
 }  // namespace net
 
 #endif  // NET_HTTP_HTTP_NETWORK_SESSION_H_