Cleans up gyp file for views example and removes duplicate code

ui/views/examples/textfield_example.h

 // 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_TEXTFIELD_EXAMPLE_H_
 #define UI_VIEWS_EXAMPLES_TEXTFIELD_EXAMPLE_H_
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/strings/string16.h"
 #include "ui/views/controls/button/button.h"
 #include "ui/views/controls/textfield/textfield_controller.h"
 #include "ui/views/examples/example_base.h"
 
 namespace views {
 
 class LabelButton;
 
 namespace examples {
 
 // TextfieldExample mimics login screen.
-class TextfieldExample : public ExampleBase,
-                         public TextfieldController,
-                         public ButtonListener {
+class VIEWS_EXAMPLES_EXPORT TextfieldExample : public ExampleBase,
+                                               public TextfieldController,
+                                               public ButtonListener {
  public:
   TextfieldExample();
   virtual ~TextfieldExample();
 
   // ExampleBase:
   virtual void CreateExampleView(View* container) OVERRIDE;
 
  private:
   // TextfieldController:
   virtual void ContentsChanged(Textfield* sender,
@@ skipping 18 matching lines @@
   LabelButton* set_;
   LabelButton* set_style_;
 
   DISALLOW_COPY_AND_ASSIGN(TextfieldExample);
 };
 
 }  // namespace examples
 }  // namespace views
 
 #endif  // UI_VIEWS_EXAMPLES_TEXTFIELD_EXAMPLE_H_