cc: Make PaintedScrollbarLayer not use ContentsScalingLayer

cc/layers/painted_scrollbar_layer_impl_unittest.cc

Index: cc/layers/painted_scrollbar_layer_impl_unittest.cc
diff --git a/cc/layers/painted_scrollbar_layer_impl_unittest.cc b/cc/layers/painted_scrollbar_layer_impl_unittest.cc
index 3994cc36ca19b323b54e004576e31ce6ddc66b94..963ac117731cdff32bfc4a9285d8006c2b00914c 100644
--- a/cc/layers/painted_scrollbar_layer_impl_unittest.cc
+++ b/cc/layers/painted_scrollbar_layer_impl_unittest.cc
@@ -36,6 +36,7 @@ TEST(PaintedScrollbarLayerImplTest, Occlusion) {
       impl.AddChildToRoot<PaintedScrollbarLayerImpl>(orientation);
   scrollbar_layer_impl->SetBounds(layer_size);
   scrollbar_layer_impl->SetContentBounds(layer_size);
+  scrollbar_layer_impl->set_internal_content_scale_and_bounds(1.f, layer_size);
   scrollbar_layer_impl->SetDrawsContent(true);
   scrollbar_layer_impl->SetThumbThickness(layer_size.width());
   scrollbar_layer_impl->SetThumbLength(500);