views/examples: Clean up cpplint warnings.

ui/views/examples/tabbed_pane_example.h

-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// 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_EXAMPLES_TABBED_PANE_EXAMPLE_H_
 #define UI_VIEWS_EXAMPLES_TABBED_PANE_EXAMPLE_H_
 #pragma once
 
+#include <string>
+
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "ui/views/controls/button/text_button.h"
 #include "ui/views/controls/tabbed_pane/tabbed_pane_listener.h"
 #include "ui/views/examples/example_base.h"
 
 namespace views {
 class TabbedPane;
 
 namespace examples {
@@ skipping 30 matching lines @@
   Button* remove_at_;
   Button* select_at_;
 
   DISALLOW_COPY_AND_ASSIGN(TabbedPaneExample);
 };
 
 }  // namespace examples
 }  // namespace views
 
 #endif  // UI_VIEWS_EXAMPLES_TABBED_PANE_EXAMPLE_H_