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

ui/base/dragdrop/gtk_dnd_util.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 UI_BASE_DRAGDROP_GTK_DND_UTIL_H_
 #define UI_BASE_DRAGDROP_GTK_DND_UTIL_H_
 
 #include <gtk/gtk.h>
 
 #include <vector>
 
-#include "base/string16.h"
+#include "base/strings/string16.h"
 #include "ui/base/ui_export.h"
 
 class GURL;
 
 namespace ui {
 
 // Registry of all internal int codes for drag and drop.
 enum {
   // Intra-application types.
   CHROME_TAB = 1 << 0,
@@ skipping 60 matching lines @@
                               std::vector<GURL>* urls);
 
 // Extracts a Netscape URL (url\ntitle) from |selection_data|.
 UI_EXPORT bool ExtractNetscapeURL(GtkSelectionData* selection_data,
                                   GURL* url,
                                   string16* title);
 
 }  // namespace ui
 
 #endif  // UI_BASE_DRAGDROP_GTK_DND_UTIL_H_