Use a direct include of strings headers in ui/, part 1.

ui/base/accessibility/accessible_text_utils.cc

 // 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.
 
 #include "ui/base/accessibility/accessible_text_utils.h"
 
 #include "base/logging.h"
-#include "base/string_util.h"
+#include "base/strings/string_util.h"
 
 namespace ui {
 
 size_t FindAccessibleTextBoundary(const string16& text,
                                   const std::vector<int>& line_breaks,
                                   TextBoundaryType boundary,
                                   size_t start_offset,
                                   TextBoundaryDirection direction) {
   size_t text_size = text.size();
   DCHECK(start_offset <= text_size);
@@ skipping 62 matching lines @@
 
     if (direction == FORWARDS_DIRECTION) {
       result++;
     } else {
       result--;
     }
   }
 }
 
 }  // Namespace ui