Paint state transition for overlay 9 patch scrollbars

ui/native_theme/native_theme_base.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_BASE_H_
 #define UI_NATIVE_THEME_NATIVE_THEME_BASE_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 15 matching lines @@
   // NativeTheme implementation:
   virtual gfx::Size GetPartSize(Part part,
                                 State state,
                                 const ExtraParams& extra) const OVERRIDE;
   virtual void Paint(SkCanvas* canvas,
                      Part part,
                      State state,
                      const gfx::Rect& rect,
                      const ExtraParams& extra) const OVERRIDE;
 
+  virtual void PaintStateTransition(SkCanvas* canvas,
+                                    Part part,
+                                    State startState,
+                                    State endState,
+                                    double progress,
+                                    const gfx::Rect& rect) const OVERRIDE;
+
  protected:
   NativeThemeBase();
   virtual ~NativeThemeBase();
 
   // Creates a gfx::Canvas wrapping an SkCanvas.
   static scoped_ptr<gfx::Canvas> CreateCanvas(SkCanvas* sk_canvas);
 
   // Draw the arrow. Used by scrollbar and inner spin button.
   virtual void PaintArrowButton(
       SkCanvas* gc,
@@ skipping 77 matching lines @@
       State state,
       const gfx::Rect& rect,
       const InnerSpinButtonExtraParams& spin_button) const;
 
   virtual void PaintProgressBar(
       SkCanvas* canvas,
       State state,
       const gfx::Rect& rect,
       const ProgressBarExtraParams& progress_bar) const;
 
+  virtual void PaintScrollbarThumbStateTransition(
+      SkCanvas* canvas,
+      State startState,
+      State endState,
+      double progress,
+      const gfx::Rect& rect) const {}
+
   void set_scrollbar_button_length(unsigned int length) {
     scrollbar_button_length_ = length;
   }
   int scrollbar_button_length() const { return scrollbar_button_length_; }
 
   bool IntersectsClipRectInt(SkCanvas* canvas,
                              int x, int y, int w, int h) const;
 
   void DrawImageInt(SkCanvas* canvas, const gfx::ImageSkia& image,
                     int src_x, int src_y, int src_w, int src_h,
@@ skipping 47 matching lines @@
 
   unsigned int scrollbar_width_;
   unsigned int scrollbar_button_length_;
 
   DISALLOW_COPY_AND_ASSIGN(NativeThemeBase);
 };
 
 }  // namespace ui
 
 #endif  // UI_NATIVE_THEME_NATIVE_THEME_BASE_H_