Adding details to most quic connection close calls.

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 679 matching lines @@
   // retransmittable frames to nullptr.
   // Saves the connection close packet for later transmission, even if the
   // writer is write blocked.
   bool WritePacket(QueuedPacket* packet);
 
   // Does the main work of WritePacket, but does not delete the packet or
   // retransmittable frames upon success.
   bool WritePacketInner(QueuedPacket* packet);
 
   // Make sure an ack we got from our peer is sane.
-  bool ValidateAckFrame(const QuicAckFrame& incoming_ack);
+  // Returns nullptr for valid acks or an error std::string if it was invalid.
+  const char* ValidateAckFrame(const QuicAckFrame& incoming_ack);
 
   // Make sure a stop waiting we got from our peer is sane.
-  bool ValidateStopWaitingFrame(const QuicStopWaitingFrame& stop_waiting);
+  // Returns nullptr if the frame is valid or an error std::string if it was
+  // invalid.
+  const char* ValidateStopWaitingFrame(
+      const QuicStopWaitingFrame& stop_waiting);
 
   // Sends a version negotiation packet to the peer.
   void SendVersionNegotiationPacket();
 
   // Clears any accumulated frames from the last received packet.
   void ClearLastFrames();
 
   // Deletes and clears any QueuedPackets.
   void ClearQueuedPackets();
 
@@ skipping 273 matching lines @@
 
   // Whether a GoAway has been received.
   bool goaway_received_;
 
   DISALLOW_COPY_AND_ASSIGN(QuicConnection);
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUIC_CONNECTION_H_