Cleans up gyp file for views example and removes duplicate code

ui/views/examples/progress_bar_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_PROGRESS_BAR_EXAMPLE_H_
 #define UI_VIEWS_EXAMPLES_PROGRESS_BAR_EXAMPLE_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "ui/views/controls/button/button.h"
 #include "ui/views/examples/example_base.h"
 
 namespace views {
 class ProgressBar;
 
 namespace examples {
 
-class ProgressBarExample : public ExampleBase, public ButtonListener {
+class VIEWS_EXAMPLES_EXPORT ProgressBarExample : public ExampleBase,
+                                                 public ButtonListener {
  public:
   ProgressBarExample();
   virtual ~ProgressBarExample();
 
   // Overridden from ExampleBase:
   virtual void CreateExampleView(View* container) OVERRIDE;
 
  private:
   // Overridden from ButtonListener:
   virtual void ButtonPressed(Button* button, const ui::Event& event) OVERRIDE;
 
   Button* minus_button_;
   Button* plus_button_;
   ProgressBar* progress_bar_;
   double current_percent_;
 
   DISALLOW_COPY_AND_ASSIGN(ProgressBarExample);
 };
 
 }  // namespace examples
 }  // namespace views
 
 #endif  // UI_VIEWS_EXAMPLES_PROGRESS_BAR_EXAMPLE_H_