Remove an unused local variable in quic_in_memory_cache.cc, only used

net/tools/quic/quic_in_memory_cache.cc

 // 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.
 
 #include "net/tools/quic/quic_in_memory_cache.h"
 
 #include "base/file_util.h"
 #include "base/files/file_enumerator.h"
 #include "base/stl_util.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 152 matching lines @@
     BalsaFrame framer;
     framer.set_balsa_headers(&response_headers);
     framer.set_balsa_visitor(&caching_visitor);
     size_t processed = 0;
     while (processed < file_contents.length() &&
            !caching_visitor.done_framing()) {
       processed += framer.ProcessInput(file_contents.c_str() + processed,
                                        file_contents.length() - processed);
     }
 
-    string response_headers_str;
-    response_headers.DumpToString(&response_headers_str);
     if (!caching_visitor.done_framing()) {
       LOG(DFATAL) << "Did not frame entire message from file: " << file.value()
                   << " (" << processed << " of " << file_contents.length()
                   << " bytes).";
     }
     if (processed < file_contents.length()) {
       // Didn't frame whole file. Assume remainder is body.
       // This sometimes happens as a result of incompatibilities between
       // BalsaFramer and wget's serialization of HTTP sans content-length.
       caching_visitor.AppendToBody(file_contents.c_str() + processed,
@@ skipping 50 matching lines @@
   } else if (StringPieceUtils::StartsWithIgnoreCase(uri, "https://")) {
     uri.remove_prefix(8);
   } else if (StringPieceUtils::StartsWithIgnoreCase(uri, "http://")) {
     uri.remove_prefix(7);
   }
   return host.as_string() + uri.as_string();
 }
 
 }  // namespace tools
 }  // namespace net