Add a probability to Alternate-Protocol support.

net/http/http_server_properties.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/http/http_server_properties.h"
 
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
 #include "base/strings/stringprintf.h"
 
@@ skipping 93 matching lines @@
 
     case kProtoUnknown:
     case kProtoHTTP11:
       break;
   }
 
   NOTREACHED() << "Invalid NextProto: " << next_proto;
   return UNINITIALIZED_ALTERNATE_PROTOCOL;
 }
 
-std::string PortAlternateProtocolPair::ToString() const {
-  return base::StringPrintf("%d:%s", port,
-                            AlternateProtocolToString(protocol));
+std::string AlternateProtocolInfo::ToString() const {
+  return base::StringPrintf("%d:%s p=%f", port,
+                            AlternateProtocolToString(protocol),
+                            probability);
 }
 
 }  // namespace net