Blink Support for Overlay Scrollbar Animation

Source/platform/scroll/Scrollbar.cpp

 /*
  * Copyright (C) 2004, 2006, 2008 Apple 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 513 matching lines @@
     m_enabled = e;
     theme()->updateEnabledState(this);
     invalidate();
 }
 
 bool Scrollbar::isOverlayScrollbar() const
 {
     return m_theme->usesOverlayScrollbars();
 }
 
+bool Scrollbar::isDuringStateTransitionAnimation() const
+{
+    return m_enabled && isOverlayScrollbar() && m_scrollableArea->isDuringStateTransitionAnimation();
+}
+
+double Scrollbar::stateTransitionProgress() const
+{
+    return m_stateTransitionProgress;
+}
+
+blink::WebThemeEngine::State Scrollbar::stateTransitionStartState() const
+{
+    return m_startState;
+}
+
+blink::WebThemeEngine::State Scrollbar::stateTransitionEndState() const
+{
+    return m_endState;
+}
+
+void Scrollbar::updateStateTransitionData(blink::WebThemeEngine::State startState, blink::WebThemeEngine::State endState, double progress)
+{
+    m_startState = startState;
+    m_endState = endState;
+    m_stateTransitionProgress = progress;
+    updateThumb();
+}
 bool Scrollbar::shouldParticipateInHitTesting()
 {
     // Non-overlay scrollbars should always participate in hit testing.
     if (!isOverlayScrollbar())
         return true;
     return m_scrollableArea->scrollAnimator()->shouldScrollbarParticipateInHitTesting(this);
 }
 
 bool Scrollbar::isWindowActive() const
 {
@@ skipping 46 matching lines @@
     if (!m_scrollableArea)
         return 0;
 
     if (m_orientation == HorizontalScrollbar)
         return m_scrollableArea->scrollPosition().x() - m_scrollableArea->minimumScrollPosition().x();
 
     return m_scrollableArea->scrollPosition().y() - m_scrollableArea->minimumScrollPosition().y();
 }
 
 } // namespace blink