Avoid string construction overhead for lookup-only HpackEntry objects.

net/spdy/hpack/hpack_decoder.cc

 // Copyright 2014 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/spdy/hpack/hpack_decoder.h"
 
 #include <utility>
 
 #include "base/basictypes.h"
 #include "base/logging.h"
@@ skipping 171 matching lines @@
   }
 
   const HpackEntry* entry = header_table_.GetByIndex(index_or_zero);
   if (entry == NULL) {
     return false;
   }
   if (entry->IsStatic()) {
     *next_name = entry->name();
   } else {
     // |entry| could be evicted as part of this insertion. Preemptively copy.
-    key_buffer_.assign(entry->name());
+    key_buffer_.assign(entry->name().data(), entry->name().size());
     *next_name = key_buffer_;
   }
   return true;
 }
 
 bool HpackDecoder::DecodeNextStringLiteral(HpackInputStream* input_stream,
                                            bool is_key,
                                            StringPiece* output) {
   if (input_stream->MatchPrefixAndConsume(kStringLiteralHuffmanEncoded)) {
     string* buffer = is_key ? &key_buffer_ : &value_buffer_;
     bool result = input_stream->DecodeNextHuffmanString(huffman_table_, buffer);
     *output = StringPiece(*buffer);
     return result;
   }
   if (input_stream->MatchPrefixAndConsume(kStringLiteralIdentityEncoded)) {
     return input_stream->DecodeNextIdentityString(output);
   }
   return false;
 }
 
 }  // namespace net