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 9eeace5b4a1747ffb2201bdbab836ce6f8187e44..4d36b699a0a402976d56b0d076ed68a7b27fe62f 100644
--- a/Source/core/rendering/RenderListBox.cpp
+++ b/Source/core/rendering/RenderListBox.cpp
@@ -99,8 +99,10 @@ 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
@@ -709,7 +711,7 @@ LayoutUnit RenderListBox::scrollLeft() const
     return 0;
 }
 
-void RenderListBox::setScrollLeft(LayoutUnit)
+void RenderListBox::setScrollLeft(LayoutUnit, ScrollBehavior)
 {
 }
 
@@ -718,14 +720,21 @@ LayoutUnit RenderListBox::scrollTop() const
     return m_indexOffset * itemHeight();
 }
 
-void RenderListBox::setScrollTop(LayoutUnit newTop)
+void RenderListBox::setScrollTop(LayoutUnit 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)
@@ -885,6 +894,22 @@ bool RenderListBox::scrollbarsCanBeActive() const
     return view->frameView()->scrollbarsCanBeActive();
 }
 
+void RenderListBox::registerForAnimation()
+{
+    frameView()->addAnimatingScrollableArea(this);
+}
+
+void RenderListBox::deregisterForAnimation()
+{
+    if (FrameView* frameView = this->frameView())
+        frameView->removeAnimatingScrollableArea(this);
+}
+
+bool RenderListBox::scheduleAnimation()
+{
+    return frameView()->scheduleAnimation();
+}
+
 IntPoint RenderListBox::minimumScrollPosition() const
 {
     return IntPoint();