Paint state transition for overlay 9 patch scrollbars

ui/native_theme/native_theme_aura.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_NATIVE_THEME_NATIVE_THEME_AURA_H_
 #define UI_NATIVE_THEME_NATIVE_THEME_AURA_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "ui/native_theme/fallback_theme.h"
@@ skipping 34 matching lines @@
       const ScrollbarTrackExtraParams& extra_params,
       const gfx::Rect& rect) const OVERRIDE;
   virtual void PaintScrollbarThumb(SkCanvas* sk_canvas,
                                    Part part,
                                    State state,
                                    const gfx::Rect& rect) const OVERRIDE;
   virtual void PaintScrollbarCorner(SkCanvas* canvas,
                                     State state,
                                     const gfx::Rect& rect) const OVERRIDE;
 
+  virtual void PaintScrollbarThumbStateTransition(SkCanvas* canvas,
+                                                  State startState,
+                                                  State endState,
+                                                  double progress,
+                                                  const gfx::Rect& rect) const
+      OVERRIDE;
+
   // Returns the NineImagePainter used to paint the specified state, creating if
   // necessary. If no image is provided for the specified state the normal state
   // images are used.
   gfx::NineImagePainter* GetOrCreatePainter(
       const int image_ids[kMaxState][9],
       State state,
       scoped_ptr<gfx::NineImagePainter> painters[kMaxState]) const;
 
   // Paints |painter| into the canvas using |rect|.
   void PaintPainter(gfx::NineImagePainter* painter,
@@ skipping 33 matching lines @@
       const uint8 fill_alphas[kMaxState],
       const int stroke_image_ids[9],
       const uint8 stroke_alphas[kMaxState]) const;
 
   // Paints |dualPainter| into the canvas using |rect| and specific alpha.
   void PaintDualPainter(DualPainter* dual_painter,
                         SkCanvas* sk_canvas,
                         const gfx::Rect& rect,
                         State state) const;
 
+  void PaintDualPainterTransition(DualPainter* dual_painter,
+                                  SkCanvas* sk_canvas,
+                                  const gfx::Rect& rect,
+                                  State startState,
+                                  State endState,
+                                  double progress) const;
+
   mutable scoped_ptr<DualPainter> scrollbar_overlay_thumb_painter_;
 
   DISALLOW_COPY_AND_ASSIGN(NativeThemeAura);
 };
 
 }  // namespace ui
 
 #endif  // UI_NATIVE_THEME_NATIVE_THEME_AURA_H_