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

content/browser/accessibility/accessibility_tree_formatter_utils_win.cc

 // 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.
 
 #include "content/browser/accessibility/accessibility_tree_formatter_utils_win.h"
 
 #include <oleacc.h>
 
 #include <map>
 #include <string>
 
 #include "base/memory/singleton.h"
-#include "base/string_util.h"
+#include "base/strings/string_util.h"
 #include "third_party/iaccessible2/ia2_api_all.h"
 
 namespace content {
 namespace {
 
 class AccessibilityRoleStateMap {
  public:
   static AccessibilityRoleStateMap* GetInstance();
 
   std::map<int32, string16> ia_role_string_map;
@@ skipping 232 matching lines @@
   }
 }
 
 string16 IAccessible2StateToString(int32 ia2_state) {
   std::vector<string16> strings;
   IAccessible2StateToStringVector(ia2_state, &strings);
   return JoinString(strings, ',');
 }
 
 }  // namespace content