Use a direct include of strings headers in base/.

base/i18n/break_iterator.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_BREAK_ITERATOR_H_
 #define BASE_I18N_BREAK_ITERATOR_H_
 
 #include "base/basictypes.h"
-#include "base/string16.h"
 #include "base/i18n/base_i18n_export.h"
+#include "base/strings/string16.h"
 
 // The BreakIterator class iterates through the words, word breaks, and
 // line breaks in a UTF-16 string.
 //
 // It provides several modes, BREAK_WORD, BREAK_LINE, and BREAK_NEWLINE,
 // which modify how characters are aggregated into the returned string.
 //
 // Under BREAK_WORD mode, once a word is encountered any non-word
 // characters are not included in the returned string (e.g. in the
 // UTF-16 equivalent of the string " foo bar! ", the word breaks are at
@@ skipping 101 matching lines @@
   // Previous and current iterator positions.
   size_t prev_, pos_;
 
   DISALLOW_COPY_AND_ASSIGN(BreakIterator);
 };
 
 }  // namespace i18n
 }  // namespace base
 
 #endif  // BASE_I18N_BREAK_ITERATOR_H_