Cleanup: Pass std::string as const reference if possible

net/quic/quic_stream_sequencer.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.
 
 #ifndef NET_QUIC_QUIC_STREAM_SEQUENCER_H_
 #define NET_QUIC_QUIC_STREAM_SEQUENCER_H_
 
 #include <map>
 #include <string>
 
 #include "base/basictypes.h"
 #include "net/base/iovec.h"
 #include "net/quic/quic_protocol.h"
 
 namespace net {
 
 namespace test {
 class QuicStreamSequencerPeer;
 }  // namespace test
 
 class QuicSession;
 class ReliableQuicStream;
 
 // Buffers frames until we have something which can be passed
 // up to the next layer.
 class NET_EXPORT_PRIVATE QuicStreamSequencer {
  public:
   // A contiguous segment received by a QUIC stream.
   struct FrameData {
-    FrameData(QuicStreamOffset offset, std::string segment);
+    FrameData(QuicStreamOffset offset, const std::string& segment);
 
     const QuicStreamOffset offset;
     std::string segment;
   };
 
   // TODO(alyssar) use something better than strings.
   // Maybe write new frames into a ring buffer, and keep track of consumed
   // bytes, and gaps.
   typedef std::list<FrameData> FrameList;
 
@@ skipping 106 matching lines @@
   // Count of the number of frames received before all previous frames were
   // received.
   int num_early_frames_received_;
 
   DISALLOW_COPY_AND_ASSIGN(QuicStreamSequencer);
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUIC_STREAM_SEQUENCER_H_