Use a direct include of strings headers in base/.

base/json/json_value_converter.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 BASE_JSON_JSON_VALUE_CONVERTER_H_
 #define BASE_JSON_JSON_VALUE_CONVERTER_H_
 
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/scoped_vector.h"
 #include "base/stl_util.h"
-#include "base/string16.h"
+#include "base/strings/string16.h"
 #include "base/strings/string_piece.h"
 #include "base/values.h"
 
 // JSONValueConverter converts a JSON value into a C++ struct in a
 // lightweight way.
 //
 // Usage:
 // For real examples, you may want to refer to _unittest.cc file.
 //
 // Assume that you have a struct like this:
@@ skipping 491 matching lines @@
 
  private:
   ScopedVector<internal::FieldConverterBase<StructType> > fields_;
 
   DISALLOW_COPY_AND_ASSIGN(JSONValueConverter);
 };
 
 }  // namespace base
 
 #endif  // BASE_JSON_JSON_VALUE_CONVERTER_H_