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

net/tools/quic/quic_spdy_client_stream.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_TOOLS_QUIC_QUIC_SPDY_CLIENT_STREAM_H_
 #define NET_TOOLS_QUIC_QUIC_SPDY_CLIENT_STREAM_H_
 
-#include "base/string_piece.h"
+#include "base/strings/string_piece.h"
 #include "net/base/io_buffer.h"
 #include "net/tools/quic/quic_reliable_client_stream.h"
 
 namespace net {
 
 class BalsaHeaders;
 
 namespace tools {
 
 class QuicClientSession;
@@ skipping 19 matching lines @@
   int ParseResponseHeaders();
 
   scoped_refptr<GrowableIOBuffer> read_buf_;
   bool response_headers_received_;
 };
 
 }  // namespace tools
 }  // namespace net
 
 #endif  // NET_TOOLS_QUIC_QUIC_SPDY_CLIENT_STREAM_H_