Replace views::Event with ui::Event.

ui/views/examples/native_theme_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/native_theme_checkbox_example.h"
 
 #include "base/stringprintf.h"
 #include "base/utf_string_conversions.h"
 #include "ui/views/controls/button/checkbox.h"
 #include "ui/views/controls/button/radio_button.h"
@@ skipping 11 matching lines @@
 }
 
 void NativeThemeCheckboxExample::CreateExampleView(View* container) {
   button_ = new Checkbox(ASCIIToUTF16("Checkbox"));
   button_->set_listener(this);
   container->SetLayoutManager(new FillLayout);
   container->AddChildView(button_);
 }
 
 void NativeThemeCheckboxExample::ButtonPressed(Button* sender,
-                                               const Event& event) {
+                                               const ui::Event& event) {
   PrintStatus(base::StringPrintf("Pressed! count: %d", ++count_).c_str());
 }
 
 }  // namespace examples
 }  // namespace views