cc: Damage layer on delegated scroll

cc/layers/layer_impl.cc

Index: cc/layers/layer_impl.cc
diff --git a/cc/layers/layer_impl.cc b/cc/layers/layer_impl.cc
index f080c924cece0061d6d41d4ffe71a9c55e0d6127..23c7a0df6f75c91dd4b3de6c2bb6311f038ab297 100644
--- a/cc/layers/layer_impl.cc
+++ b/cc/layers/layer_impl.cc
@@ -1079,6 +1079,11 @@ bool LayerImpl::IsExternalFlingActive() const {
          scroll_offset_delegate_->IsExternalFlingActive();
 }
 
+void LayerImpl::DidScroll() {
+  NoteLayerPropertyChangedForSubtree();
+  ScrollbarParametersDidChange(false);
+}
+
 void LayerImpl::SetScrollOffset(const gfx::ScrollOffset& scroll_offset) {
   SetScrollOffsetAndDelta(scroll_offset, ScrollDelta());
 }
@@ -1122,8 +1127,7 @@ void LayerImpl::SetScrollOffsetAndDelta(const gfx::ScrollOffset& scroll_offset,
   }
 
   if (changed) {
-    NoteLayerPropertyChangedForSubtree();
-    ScrollbarParametersDidChange(false);
+    DidScroll();
   }
 }