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

net/base/hash_value.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_BASE_HASH_VALUE_H_
 #define NET_BASE_HASH_VALUE_H_
 
 #include <string.h>
 
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
-#include "base/string_piece.h"
+#include "base/strings/string_piece.h"
 #include "build/build_config.h"
 #include "net/base/net_export.h"
 
 namespace net {
 
 struct NET_EXPORT SHA1HashValue {
   bool Equals(const SHA1HashValue& other) const;
 
   unsigned char data[20];
 };
@@ skipping 91 matching lines @@
 
 // IsSHA1HashInSortedArray returns true iff |hash| is in |array|, a sorted
 // array of SHA1 hashes.
 bool IsSHA1HashInSortedArray(const SHA1HashValue& hash,
                              const uint8* array,
                              size_t array_byte_len);
 
 }  // namespace net
 
 #endif  // NET_BASE_HASH_VALUE_H_