[SPDY] Do not advertise SPDY/2 by default

net/spdy/spdy_session_pool.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/spdy/spdy_session_pool.h"
 
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
 #include "base/values.h"
 #include "net/base/address_list.h"
@@ skipping 36 matching lines @@
       resolver_(resolver),
       verify_domain_authentication_(true),
       enable_sending_initial_data_(true),
       force_single_domain_(force_single_domain),
       enable_ip_pooling_(enable_ip_pooling),
       enable_credential_frames_(enable_credential_frames),
       enable_compression_(enable_compression),
       enable_ping_based_connection_checking_(
           enable_ping_based_connection_checking),
       // TODO(akalin): Force callers to have a valid value of
-      // |default_protocol_|. Or at least make the default be
-      // kProtoSPDY3.
+      // |default_protocol_|.
       default_protocol_(
           (default_protocol == kProtoUnknown) ?
-          kProtoSPDY2 : default_protocol),
+          kProtoSPDY3 : default_protocol),
       stream_initial_recv_window_size_(stream_initial_recv_window_size),
       initial_max_concurrent_streams_(initial_max_concurrent_streams),
       max_concurrent_streams_limit_(max_concurrent_streams_limit),
       time_func_(time_func),
       trusted_spdy_proxy_(
           HostPortPair::FromString(trusted_spdy_proxy)) {
   DCHECK(default_protocol_ >= kProtoSPDYMinimumVersion &&
          default_protocol_ <= kProtoSPDYMaximumVersion);
   NetworkChangeNotifier::AddIPAddressObserver(this);
   if (ssl_config_service_.get())
@@ skipping 314 matching lines @@
     if (idle_only && (*it)->is_active())
       continue;
 
     (*it)->CloseSessionOnError(error, description);
     DCHECK(!IsSessionAvailable(*it));
     DCHECK(!*it);
   }
 }
 
 }  // namespace net