Use a direct include of strings headers in ui/, part 3.

ui/views/controls/textfield/textfield_controller.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.
 
 #ifndef UI_VIEWS_CONTROLS_TEXTFIELD_TEXTFIELD_CONTROLLER_H_
 #define UI_VIEWS_CONTROLS_TEXTFIELD_TEXTFIELD_CONTROLLER_H_
 
 #include <set>
 
-#include "base/string16.h"
+#include "base/strings/string16.h"
 #include "ui/base/dragdrop/os_exchange_data.h"
 #include "ui/views/views_export.h"
 
 namespace ui {
 class KeyEvent;
 class MouseEvent;
 class SimpleMenuModel;
 }  // namespace ui
 
 namespace views {
@@ skipping 78 matching lines @@
   // Execute context menu command specified by |command_id|.
   virtual void ExecuteCommand(int command_id, int event_flag) {}
 
  protected:
   virtual ~TextfieldController() {}
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_TEXTFIELD_TEXTFIELD_CONTROLLER_H_