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

ui/base/resource/data_pack.cc

 // 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.
 
 #include "ui/base/resource/data_pack.h"
 
 #include <errno.h>
 
 #include "base/file_util.h"
 #include "base/files/memory_mapped_file.h"
 #include "base/logging.h"
 #include "base/memory/ref_counted_memory.h"
 #include "base/metrics/histogram.h"
-#include "base/string_piece.h"
+#include "base/strings/string_piece.h"
 
 // For details of the file layout, see
 // http://dev.chromium.org/developers/design-documents/linuxresourcesandlocalizedstrings
 
 namespace {
 
 static const uint32 kFileFormatVersion = 4;
 // Length of file header: version, entry count and text encoding type.
 static const size_t kHeaderLength = 2 * sizeof(uint32) + sizeof(uint8);
 
@@ skipping 272 matching lines @@
       return false;
     }
   }
 
   file_util::CloseFile(file);
 
   return true;
 }
 
 }  // namespace ui