Adds a DebugString() method to QuicHeaderList.

net/quic/quic_header_list.h

 // Copyright (c) 2016 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_QUIC_QUIC_HEADER_LIST_H_
 #define NET_QUIC_QUIC_HEADER_LIST_H_
 
 #include <deque>
 #include <functional>
 
 #include "base/strings/string_piece.h"
 #include "net/base/net_export.h"
 #include "net/quic/quic_bug_tracker.h"
 #include "net/spdy/spdy_header_block.h"
 #include "net/spdy/spdy_headers_handler_interface.h"
 
 namespace net {
 
 // A simple class that accumulates header pairs
 class NET_EXPORT_PRIVATE QuicHeaderList : public SpdyHeadersHandlerInterface {
  public:
   typedef std::deque<std::pair<std::string, std::string>> ListType;
+  typedef ListType::const_iterator const_iterator;
 
   QuicHeaderList();
   QuicHeaderList(QuicHeaderList&& other);
   QuicHeaderList(const QuicHeaderList& other);
   QuicHeaderList& operator=(QuicHeaderList&& other);
   QuicHeaderList& operator=(const QuicHeaderList& other);
   ~QuicHeaderList() override;
 
   // From SpdyHeadersHandlerInteface.
   void OnHeaderBlockStart() override;
   void OnHeader(base::StringPiece name, base::StringPiece value) override;
   void OnHeaderBlockEnd(size_t uncompressed_header_bytes) override;
 
   void Clear();
 
-  ListType::const_iterator begin() const { return header_list_.begin(); }
-  ListType::const_iterator end() const { return header_list_.end(); }
+  const_iterator begin() const { return header_list_.begin(); }
+  const_iterator end() const { return header_list_.end(); }
 
   bool empty() const { return header_list_.empty(); }
   size_t uncompressed_header_bytes() const {
     return uncompressed_header_bytes_;
   }
 
+  std::string DebugString() const;
+
  private:
   std::deque<std::pair<std::string, std::string>> header_list_;
   size_t uncompressed_header_bytes_;
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUIC_HEADER_LIST_H_