[SPDY] Do not advertise SPDY/2 by default

net/http/http_network_layer.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_LAYER_H_
 #define NET_HTTP_HTTP_NETWORK_LAYER_H_
 
 #include <string>
 
 #include "base/memory/ref_counted.h"
@@ skipping 18 matching lines @@
   virtual ~HttpNetworkLayer();
 
   // Create a transaction factory that instantiate a network layer over an
   // existing network session. Network session contains some valuable
   // information (e.g. authentication data) that we want to share across
   // multiple network layers. This method exposes the implementation details
   // of a network layer, use this method with an existing network layer only
   // when network session is shared.
   static HttpTransactionFactory* CreateFactory(HttpNetworkSession* session);
 
-  // Forces an alternate protocol of SPDY/2 on port 443.
+  // Forces an alternate protocol of SPDY/3 on port 443.
   // TODO(rch): eliminate this method.
   static void ForceAlternateProtocol();
 
   // HttpTransactionFactory methods:
   virtual int CreateTransaction(RequestPriority priority,
                                 scoped_ptr<HttpTransaction>* trans,
                                 HttpTransactionDelegate* delegate) OVERRIDE;
   virtual HttpCache* GetCache() OVERRIDE;
   virtual HttpNetworkSession* GetSession() OVERRIDE;
 
   // base::PowerObserver methods:
   virtual void OnSuspend() OVERRIDE;
   virtual void OnResume() OVERRIDE;
 
  private:
   const scoped_refptr<HttpNetworkSession> session_;
   bool suspended_;
 };
 
 }  // namespace net
 
 #endif  // NET_HTTP_HTTP_NETWORK_LAYER_H_