cc: Clean up root_layer code in LTI

cc/layers/layer_unittest.cc

 // Copyright 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/layers/layer.h"
 
 #include <stddef.h>
 
 #include "base/threading/thread_task_runner_handle.h"
 #include "cc/animation/animation_host.h"
@@ skipping 1715 matching lines @@
 }
 
 TEST_F(LayerTest, PushPropertiesAccumulatesUpdateRect) {
   scoped_refptr<Layer> test_layer = Layer::Create();
   std::unique_ptr<LayerImpl> impl_layer =
       LayerImpl::Create(host_impl_.active_tree(), 1);
 
   EXPECT_SET_NEEDS_FULL_TREE_SYNC(1,
                                   layer_tree_host_->SetRootLayer(test_layer));
 
-  host_impl_.active_tree()->SetRootLayer(std::move(impl_layer));
+  host_impl_.active_tree()->SetRootLayerForTesting(std::move(impl_layer));
   host_impl_.active_tree()->BuildLayerListForTesting();
   LayerImpl* impl_layer_ptr = host_impl_.active_tree()->LayerById(1);
   test_layer->SetNeedsDisplayRect(gfx::Rect(5, 5));
   test_layer->PushPropertiesTo(impl_layer_ptr);
   EXPECT_FLOAT_RECT_EQ(gfx::RectF(0.f, 0.f, 5.f, 5.f),
                        impl_layer_ptr->update_rect());
 
   // The LayerImpl's update_rect() should be accumulated here, since we did not
   // do anything to clear it.
   test_layer->SetNeedsDisplayRect(gfx::Rect(10, 10, 5, 5));
@@ skipping 769 matching lines @@
   EXPECT_EQ(MutableProperty::kNone, impl_layer->mutable_properties());
 
   test_layer->PushPropertiesTo(impl_layer.get());
 
   EXPECT_EQ(2lu, impl_layer->element_id());
   EXPECT_EQ(MutableProperty::kTransform, impl_layer->mutable_properties());
 }
 
 }  // namespace
 }  // namespace cc