Use a direct include of strings headers in base/.

base/i18n/icu_string_conversions.h

 // Copyright (c) 2011 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_I18N_ICU_STRING_CONVERSIONS_H_
 #define BASE_I18N_ICU_STRING_CONVERSIONS_H_
 
 #include <string>
 
 #include "base/i18n/base_i18n_export.h"
 #include "base/i18n/i18n_constants.h"
-#include "base/string16.h"
+#include "base/strings/string16.h"
 
 namespace base {
 
 // Defines the error handling modes of UTF16ToCodepage, CodepageToUTF16,
 // WideToCodepage and CodepageToWide.
 class OnStringConversionError {
  public:
   enum Type {
     // The function will return failure. The output buffer will be empty.
     FAIL,
@@ skipping 38 matching lines @@
 
 // Converts from any codepage to UTF-8 and ensures the resulting UTF-8 is
 // normalized.
 BASE_I18N_EXPORT bool ConvertToUtf8AndNormalize(const std::string& text,
                                                 const std::string& charset,
                                                 std::string* result);
 
 }  // namespace base
 
 #endif  // BASE_I18N_ICU_STRING_CONVERSIONS_H_