Fix classes that have too many virtuals for inline constructors.

net/quic/quic_connection.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.
 //
 // The entity that handles framing writes for a Quic client or server.
 // Each QuicSession will have a connection associated with it.
 //
 // On the server side, the Dispatcher handles the raw reads, and hands off
 // packets via ProcessUdpPacket for framing and processing.
 //
@@ skipping 230 matching lines @@
   virtual void OnResumeConnectionState(
       const CachedNetworkParameters& cached_network_params) {}
 
   // Called when the connection parameters are set from the supplied
   // |config|.
   virtual void OnSetFromConfig(const QuicConfig& config) {}
 
   // Called when RTT may have changed, including when an RTT is read from
   // the config.
   virtual void OnRttChanged(QuicTime::Delta rtt) const {}
+
+ protected:
+  QuicConnectionDebugVisitor() = default;
 };
 
 class NET_EXPORT_PRIVATE QuicConnectionHelperInterface {
  public:
   virtual ~QuicConnectionHelperInterface() {}
 
   // Returns a QuicClock to be used for all time related functions.
   virtual const QuicClock* GetClock() const = 0;
 
   // Returns a QuicRandom to be used for all random number related functions.
@@ skipping 722 matching lines @@
 
   // Whether a GoAway has been received.
   bool goaway_received_;
 
   DISALLOW_COPY_AND_ASSIGN(QuicConnection);
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUIC_CONNECTION_H_