cc: Clean up root_layer code in LTI

cc/layers/layer_utils_unittest.cc

 // Copyright 2014 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_utils.h"
 
 #include "cc/animation/animation_host.h"
 #include "cc/animation/animation_id_provider.h"
 #include "cc/animation/transform_operations.h"
 #include "cc/layers/layer_impl.h"
@@ skipping 63 matching lines @@
         ->test_properties()
         ->AddChild(LayerImpl::Create(host_impl->active_tree(), 6));
     root->test_properties()
         ->children[1]
         ->test_properties()
         ->children[0]
         ->test_properties()
         ->children[0]
         ->test_properties()
         ->AddChild(LayerImpl::Create(host_impl->active_tree(), 7));
-    host_impl->active_tree()->SetRootLayer(std::move(root));
+    host_impl->active_tree()->SetRootLayerForTesting(std::move(root));
     return root_ptr;
   }
 
   FakeImplTaskRunnerProvider task_runner_provider_;
   TestSharedBitmapManager shared_bitmap_manager_;
   TestTaskGraphRunner task_graph_runner_;
   FakeLayerTreeHostImpl host_impl_;
   LayerImpl* root_;
   LayerImpl* parent1_;
   LayerImpl* parent2_;
@@ skipping 479 matching lines @@
   // Same as RotateXWithPerspectiveUnderAncestorsWithPositionOr2DTransform test,
   // except for the perspective calculations.
 
   gfx::BoxF expected(295.f, 180.f, -25.f, 50.f, 50.f, 50.f);
   EXPECT_BOXF_EQ(expected, box);
 }
 
 }  // namespace
 
 }  // namespace cc