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

net/spdy/spdy_frame_reader.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_SPDY_SPDY_FRAME_READER_H_
 #define NET_SPDY_SPDY_FRAME_READER_H_
 
 #include "base/basictypes.h"
-#include "base/string_piece.h"
+#include "base/strings/string_piece.h"
 #include "net/base/net_export.h"
 
 namespace net {
 
 // Used for reading SPDY frames. Though there isn't really anything terribly
 // SPDY-specific here, it's a helper class that's useful when doing SPDY
 // framing.
 //
 // To use, simply construct a SpdyFramerReader using the underlying buffer that
 // you'd like to read fields from, then call one of the Read*() methods to
@@ skipping 94 matching lines @@
   // The length of the data buffer that we're reading from.
   const size_t len_;
 
   // The location of the next read from our data buffer.
   size_t ofs_;
 };
 
 }  // namespace net
 
 #endif  // NET_SPDY_SPDY_FRAME_READER_H_