Convert scroll offsets to use SyncedProperty.

cc/trees/layer_tree_host_common.cc

Index: cc/trees/layer_tree_host_common.cc
diff --git a/cc/trees/layer_tree_host_common.cc b/cc/trees/layer_tree_host_common.cc
index 3e70aeb38d24ba19239123b16c3b32a16d3cacfd..b723d01932110363376cfa148fb47f588f406ba6 100644
--- a/cc/trees/layer_tree_host_common.cc
+++ b/cc/trees/layer_tree_host_common.cc
@@ -46,19 +46,19 @@ static void SortLayers(LayerImplList::iterator first,
 
 template <typename LayerType>
 static gfx::Vector2dF GetEffectiveScrollDelta(LayerType* layer) {
-  gfx::Vector2dF scroll_delta = layer->ScrollDelta();
+  gfx::ScrollOffset scroll_delta = layer->ScrollDelta();
   // The scroll parent's scroll delta is the amount we've scrolled on the
   // compositor thread since the commit for this layer tree's source frame.
   // we last reported to the main thread. I.e., it's the discrepancy between
   // a scroll parent's scroll delta and offset, so we must add it here.
   if (layer->scroll_parent())
     scroll_delta += layer->scroll_parent()->ScrollDelta();
-  return scroll_delta;
+  return gfx::Vector2dF(scroll_delta.x(), scroll_delta.y());
 }
 
 template <typename LayerType>
-static gfx::ScrollOffset GetEffectiveTotalScrollOffset(LayerType* layer) {
-  gfx::ScrollOffset offset = layer->TotalScrollOffset();
+static gfx::ScrollOffset GetEffectiveCurrentScrollOffset(LayerType* layer) {
+  gfx::ScrollOffset offset = layer->CurrentScrollOffset();
   // The scroll parent's total scroll offset (scroll offset + scroll delta)
   // can't be used because its scroll offset has already been applied to the
   // scroll children's positions by the main thread layer positioning code.
@@ -1666,7 +1666,7 @@ static void CalculateDrawPropertiesInternal(
         layer->parent()->screen_space_transform_is_animating();
   }
   gfx::Point3F transform_origin = layer->transform_origin();
-  gfx::ScrollOffset scroll_offset = GetEffectiveTotalScrollOffset(layer);
+  gfx::ScrollOffset scroll_offset = GetEffectiveCurrentScrollOffset(layer);
   gfx::PointF position =
       layer->position() - ScrollOffsetToVector2dF(scroll_offset);
   gfx::Transform combined_transform = data_from_ancestor.parent_matrix;