cc: Clean up root_layer code in LTI

cc/input/scrollbar_animation_controller_linear_fade_unittest.cc

Index: cc/input/scrollbar_animation_controller_linear_fade_unittest.cc
diff --git a/cc/input/scrollbar_animation_controller_linear_fade_unittest.cc b/cc/input/scrollbar_animation_controller_linear_fade_unittest.cc
index 1f6b20a668db87c6d3dec79810eb85cc0c474840..3303d23411217af84b9cd6ae2b12af0727f7a9b5 100644
--- a/cc/input/scrollbar_animation_controller_linear_fade_unittest.cc
+++ b/cc/input/scrollbar_animation_controller_linear_fade_unittest.cc
@@ -64,7 +64,7 @@ class ScrollbarAnimationControllerLinearFadeTest
     LayerImpl* scroll_layer_ptr = scroll_layer.get();
     scroll_layer->test_properties()->AddChild(std::move(scrollbar));
     clip->test_properties()->AddChild(std::move(scroll_layer));
-    host_impl_.active_tree()->SetRootLayer(std::move(clip));
+    host_impl_.active_tree()->SetRootLayerForTesting(std::move(clip));
 
     scrollbar_layer_->SetScrollLayerId(scroll_layer_ptr->id());
     clip_layer_->SetBounds(gfx::Size(100, 100));