Blink Support for Overlay Scrollbar Animation

Source/platform/scroll/ScrollbarThemeClient.h

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 13 matching lines @@
  */
 
 #ifndef ScrollbarThemeClient_h
 #define ScrollbarThemeClient_h
 
 #include "platform/PlatformExport.h"
 #include "platform/geometry/IntPoint.h"
 #include "platform/geometry/IntRect.h"
 #include "platform/geometry/IntSize.h"
 #include "platform/scroll/ScrollTypes.h"
+#include "public/platform/WebThemeEngine.h"
 #include "wtf/PassOwnPtr.h"
 #include "wtf/Vector.h"
 
 namespace WebCore {
 
 class Widget;
 
 class PLATFORM_EXPORT ScrollbarThemeClient {
 public:
     virtual int x() const = 0;
@@ skipping 33 matching lines @@
     virtual ScrollbarPart pressedPart() const = 0;
     virtual ScrollbarPart hoveredPart() const = 0;
 
     virtual void styleChanged() = 0;
 
     virtual bool enabled() const = 0;
     virtual void setEnabled(bool) = 0;
 
     virtual bool isOverlayScrollbar() const = 0;
 
+    virtual bool isDuringStateTransitionAnimation() const
+    {
+        return false;
+    }
+    virtual double stateTransitionProgress() const
+    {
+        return 0;
+    }
+    virtual blink::WebThemeEngine::State stateTransitionStartState() const
+    {
+        return blink::WebThemeEngine::StateNormal;
+    }
+    virtual blink::WebThemeEngine::State stateTransitionEndState() const
+    {
+        return blink::WebThemeEngine::StateNormal;
+    }
+
     virtual bool isAlphaLocked() const = 0;
     virtual void setIsAlphaLocked(bool) = 0;
 
 protected:
     virtual ~ScrollbarThemeClient() { }
 };
 
 } // namespace WebCore
 
 #endif // ScollbarThemeClient_h