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

ui/views/examples/checkbox_example.cc

 // 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.
 
 #include "ui/views/examples/checkbox_example.h"
 
-#include "base/stringprintf.h"
+#include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #include "ui/views/controls/button/checkbox.h"
 #include "ui/views/controls/button/radio_button.h"
 #include "ui/views/layout/fill_layout.h"
 
 namespace views {
 namespace examples {
 
 CheckboxExample::CheckboxExample() : ExampleBase("Checkbox"), count_(0) {
 }
 
 CheckboxExample::~CheckboxExample() {
 }
 
 void CheckboxExample::CreateExampleView(View* container) {
   button_ = new Checkbox(ASCIIToUTF16("Checkbox"));
   button_->set_listener(this);
   container->SetLayoutManager(new FillLayout);
   container->AddChildView(button_);
 }
 
 void CheckboxExample::ButtonPressed(Button* sender, const ui::Event& event) {
   PrintStatus("Pressed! count: %d", ++count_);
 }
 
 }  // namespace examples
 }  // namespace views