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

ui/base/clipboard/custom_data_helper.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.
 //
 // Due to restrictions of most operating systems, we don't directly map each
 // type of custom data to a native data transfer type. Instead, we serialize
 // each key-value pair into the pickle as a pair of string objects, and then
 // write the binary data in the pickle to the native data transfer object.
 
 #ifndef UI_BASE_CLIPBOARD_CUSTOM_DATA_HELPER_H_
 #define UI_BASE_CLIPBOARD_CUSTOM_DATA_HELPER_H_
 
 #include <map>
 #include <vector>
 
-#include "base/string16.h"
+#include "base/strings/string16.h"
 #include "ui/base/ui_export.h"
 
 class Pickle;
 
 #if defined(OS_MACOSX)
 #ifdef __OBJC__
 @class NSString;
 #else
 class NSString;
 #endif
@@ skipping 17 matching lines @@
 UI_EXPORT void ReadCustomDataIntoMap(const void* data,
                                      size_t data_length,
                                      std::map<string16, string16>* result);
 
 UI_EXPORT void WriteCustomDataToPickle(const std::map<string16, string16>& data,
                                        Pickle* pickle);
 
 }  // namespace ui
 
 #endif  // UI_BASE_CLIPBOARD_CLIPBOARD_H_