Add the button style for combobox

ui/views/controls/button/label_button.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_CONTROLS_BUTTON_LABEL_BUTTON_H_
 #define UI_VIEWS_CONTROLS_BUTTON_LABEL_BUTTON_H_
 
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/gfx/font.h"
 #include "ui/gfx/image/image_skia.h"
 #include "ui/views/controls/button/custom_button.h"
 #include "ui/views/controls/image_view.h"
 #include "ui/views/controls/label.h"
 #include "ui/views/native_theme_delegate.h"
 
 namespace views {
 
 class Painter;
 
 // LabelButton is an alternative to TextButton, it's not focusable by default.
 class VIEWS_EXPORT LabelButton : public CustomButton,
                                  public NativeThemeDelegate {
  public:
+  // The length of the hover fade animation.
+  static const int kHoverAnimationDurationMs;
+
   static const char kViewClassName[];
 
   LabelButton(ButtonListener* listener, const string16& text);
   virtual ~LabelButton();
 
   // Get or set the image shown for the specified button state.
   // GetImage returns the image for STATE_NORMAL if the state's image is empty.
   virtual const gfx::ImageSkia& GetImage(ButtonState for_state);
   void SetImage(ButtonState for_state, const gfx::ImageSkia& image);
 
@@ skipping 109 matching lines @@
   ButtonStyle style_;
 
   scoped_ptr<Painter> focus_painter_;
 
   DISALLOW_COPY_AND_ASSIGN(LabelButton);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_BUTTON_LABEL_BUTTON_H_