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

ui/aura/client/cursor_client.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_AURA_CLIENT_CURSOR_CLIENT_H_
 #define UI_AURA_CLIENT_CURSOR_CLIENT_H_
 
-#include "base/string16.h"
+#include "base/strings/string16.h"
 #include "ui/aura/aura_export.h"
 #include "ui/gfx/native_widget_types.h"
 
 namespace gfx {
 class Display;
 }
 
 namespace aura {
 class Window;
 namespace client {
@@ skipping 55 matching lines @@
 
 // Sets/Gets the activation client for the specified window.
 AURA_EXPORT void SetCursorClient(Window* window,
                                  CursorClient* client);
 AURA_EXPORT CursorClient* GetCursorClient(Window* window);
 
 }  // namespace client
 }  // namespace aura
 
 #endif  // UI_AURA_CLIENT_CURSOR_CLIENT_H_