Implement CSSOM Smooth Scroll API

Source/core/rendering/RenderListBox.cpp

Index: Source/core/rendering/RenderListBox.cpp
diff --git a/Source/core/rendering/RenderListBox.cpp b/Source/core/rendering/RenderListBox.cpp
index 98e40b489503361520ebd2f17a0374170e44ac42..a630593c351269c4e9ce8fc103477fa926383391 100644
--- a/Source/core/rendering/RenderListBox.cpp
+++ b/Source/core/rendering/RenderListBox.cpp
@@ -100,8 +100,10 @@ RenderListBox::~RenderListBox()
 {
     setHasVerticalScrollbar(false);
 
-    if (FrameView* frameView = frame()->view())
+    if (FrameView* frameView = frame()->view()) {
         frameView->removeScrollableArea(this);
+        frameView->removeAnimatingScrollableArea(this);
+    }
 }
 
 // FIXME: Instead of this hack we should add a ShadowRoot to <select> with no insertion point
@@ -697,7 +699,7 @@ int RenderListBox::scrollLeft() const
     return 0;
 }
 
-void RenderListBox::setScrollLeft(int)
+void RenderListBox::setScrollLeft(int, ScrollBehavior)
 {
 }
 
@@ -706,14 +708,21 @@ int RenderListBox::scrollTop() const
     return m_indexOffset * itemHeight();
 }
 
-void RenderListBox::setScrollTop(int newTop)
+void RenderListBox::setScrollTop(int newTop, ScrollBehavior scrollBehavior)
 {
+    cancelProgrammaticScrollAnimation();
+
     // Determine an index and scroll to it.
     int index = newTop / itemHeight();
     if (index < 0 || index >= numItems() || index == m_indexOffset)
         return;
 
-    scrollToOffsetWithoutAnimation(VerticalScrollbar, index);
+    if (scrollBehavior == ScrollBehaviorAuto)
+        scrollBehavior = style()->scrollBehavior();
+    if (scrollBehavior == ScrollBehaviorSmooth)
+        programmaticallyScrollSmoothlyToOffset(FloatPoint(0, index));
+    else
+        scrollToOffsetWithoutAnimation(VerticalScrollbar, index);
 }
 
 bool RenderListBox::nodeAtPoint(const HitTestRequest& request, HitTestResult& result, const HitTestLocation& locationInContainer, const LayoutPoint& accumulatedOffset, HitTestAction hitTestAction)
@@ -873,6 +882,26 @@ bool RenderListBox::scrollbarsCanBeActive() const
     return view->frameView()->scrollbarsCanBeActive();
 }
 
+bool RenderListBox::registerForAnimation()
+{
+    if (FrameView* frameView = frame()->view())
+        return frameView->addAnimatingScrollableArea(this);
+    return false;
+}
+
+void RenderListBox::deregisterForAnimation()
+{
+    if (FrameView* frameView = frame()->view())
+        frameView->removeAnimatingScrollableArea(this);
+}
+
+bool RenderListBox::scheduleAnimation()
+{
+    if (FrameView* frameView = frame()->view())
+        return frameView->scheduleAnimation();
+    return false;
+}
+
 IntPoint RenderListBox::minimumScrollPosition() const
 {
     return IntPoint();