net: Update the include paths of base/string_piece.h to its new location.

net/quic/quic_packet_creator.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.
 //
 // Accumulates frames for the next packet until more frames no longer fit or
 // it's time to create a packet from them.  Also provides packet creation of
 // FEC packets based on previously created packets.
 
 #ifndef NET_QUIC_QUIC_PACKET_CREATOR_H_
 #define NET_QUIC_QUIC_PACKET_CREATOR_H_
 
 #include <utility>
 #include <vector>
 
 #include "base/memory/scoped_ptr.h"
-#include "base/string_piece.h"
+#include "base/strings/string_piece.h"
 #include "net/quic/quic_fec_group.h"
 #include "net/quic/quic_framer.h"
 #include "net/quic/quic_protocol.h"
 
 namespace net {
 namespace test {
 class QuicPacketCreatorPeer;
 }
 
 class QuicRandom;
@@ skipping 136 matching lines @@
   size_t packet_size_;
   QuicFrames queued_frames_;
   scoped_ptr<RetransmittableFrames> queued_retransmittable_frames_;
 
   DISALLOW_COPY_AND_ASSIGN(QuicPacketCreator);
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUIC_PACKET_CREATOR_H_