cc: Clean up root_layer code in LTI

cc/test/fake_layer_tree_host.cc

Index: cc/test/fake_layer_tree_host.cc
diff --git a/cc/test/fake_layer_tree_host.cc b/cc/test/fake_layer_tree_host.cc
index 2756987325f569168c0edc4dd904f4adebd2540f..4d214fb9f535a4c73146ff5c2655397855f9ba1d 100644
--- a/cc/test/fake_layer_tree_host.cc
+++ b/cc/test/fake_layer_tree_host.cc
@@ -103,7 +103,7 @@ LayerImpl* FakeLayerTreeHost::CommitAndCreateLayerImplTree() {
   }
 
   active_tree()->UpdatePropertyTreesForBoundsDelta();
-  return active_tree()->root_layer();
+  return active_tree()->root_layer_for_testing();
 }
 
 LayerImpl* FakeLayerTreeHost::CommitAndCreatePendingTree() {
@@ -114,7 +114,7 @@ LayerImpl* FakeLayerTreeHost::CommitAndCreatePendingTree() {
   animation_host()->PushPropertiesTo(host_impl_.animation_host());
 
   pending_tree()->UpdatePropertyTreeScrollOffset(property_trees());
-  return pending_tree()->root_layer();
+  return pending_tree()->root_layer_for_testing();
 }
 
 }  // namespace cc