Add logging to the QUIC write path.

net/quic/quic_packet_generator.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.
 //
 // Responsible for generating packets on behalf of a QuicConnection.
 // Packets are serialized just-in-time.  Control frames are queued.
 // Ack and Feedback frames will be requested from the Connection
 // just-in-time.  When a packet needs to be sent, the Generator
 // will serialize a packet and pass it to QuicConnection::SendOrQueuePacket()
 //
@@ skipping 52 matching lines @@
    public:
     virtual ~DelegateInterface() {}
     virtual bool CanWrite(Retransmission retransmission,
                           HasRetransmittableData retransmittable) = 0;
     virtual QuicAckFrame* CreateAckFrame() = 0;
     virtual QuicCongestionFeedbackFrame* CreateFeedbackFrame() = 0;
     // Takes ownership of |packet.packet| and |packet.retransmittable_frames|.
     virtual bool OnSerializedPacket(const SerializedPacket& packet) = 0;
   };
 
+  // Interface which gets callbacks from the QuicPacketGenerator at interesting
+  // points.  Implementations must not mutate the state of the generator
+  // as a result of these callbacks.
+  class NET_EXPORT_PRIVATE DebugDelegateInterface {
+   public:
+    virtual ~DebugDelegateInterface() {}
+
+    // Called when a frame has been added to the current packet.
+    virtual void OnFrameAddedToPacket(const QuicFrame& frame) = 0;
+  };
+
   QuicPacketGenerator(DelegateInterface* delegate,
+                      DebugDelegateInterface* debug_delegate,
                       QuicPacketCreator* creator);
 
   virtual ~QuicPacketGenerator();
 
   void SetShouldSendAck(bool also_send_feedback);
   void AddControlFrame(const QuicFrame& frame);
   QuicConsumedData ConsumeData(QuicStreamId id,
                                base::StringPiece data,
                                QuicStreamOffset offset,
                                bool fin);
 
   // Disables flushing.
   void StartBatchOperations();
   // Enables flushing and flushes queued data.
   void FinishBatchOperations();
 
   bool HasQueuedFrames() const;
 
+  void set_debug_delegate(DebugDelegateInterface* debug_delegate) {
+    debug_delegate_ = debug_delegate;
+  }
+
  private:
   void SendQueuedFrames();
 
   bool HasPendingFrames() const;
   bool AddNextPendingFrame();
+
+  bool AddFrame(const QuicFrame& frame);
   void SerializeAndSendPacket();
 
   DelegateInterface* delegate_;
+  DebugDelegateInterface* debug_delegate_;
 
   QuicPacketCreator* packet_creator_;
   QuicFrames queued_control_frames_;
   bool should_flush_;
   bool should_send_ack_;
   scoped_ptr<QuicAckFrame> pending_ack_frame_;
   scoped_ptr<QuicCongestionFeedbackFrame> pending_feedback_frame_;
   bool should_send_feedback_;
 
   DISALLOW_COPY_AND_ASSIGN(QuicPacketGenerator);
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUIC_PACKET_GENERATOR_H_