Cleans up gyp file for views example and removes duplicate code

ui/views/examples/widget_example.h

 // 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.
 
 #ifndef UI_VIEWS_EXAMPLES_WIDGET_EXAMPLE_H_
 #define UI_VIEWS_EXAMPLES_WIDGET_EXAMPLE_H_
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "ui/views/controls/button/button.h"
 #include "ui/views/examples/example_base.h"
 #include "ui/views/widget/widget.h"
 
 namespace views {
 namespace examples {
 
 // WidgetExample demonstrates how to create a popup widget.
-class WidgetExample : public ExampleBase, public ButtonListener {
+class VIEWS_EXAMPLES_EXPORT WidgetExample : public ExampleBase,
+                                            public ButtonListener {
  public:
   WidgetExample();
   virtual ~WidgetExample();
 
   // Overridden from ExampleBase:
   virtual void CreateExampleView(View* container) OVERRIDE;
 
  private:
   // Button tags used to identify various commands.
   enum Command {
@@ skipping 12 matching lines @@
   // Overridden from ButtonListener:
   virtual void ButtonPressed(Button* sender, const ui::Event& event) OVERRIDE;
 
   DISALLOW_COPY_AND_ASSIGN(WidgetExample);
 };
 
 }  // namespace examples
 }  // namespace views
 
 #endif  // UI_VIEWS_EXAMPLES_WIDGET_EXAMPLE_H_