cc: Clean up root_layer code in LTI

cc/layers/render_surface_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/append_quads_data.h"
 #include "cc/layers/layer_impl.h"
 #include "cc/layers/render_pass_sink.h"
 #include "cc/layers/render_surface_impl.h"
 #include "cc/quads/shared_quad_state.h"
 #include "cc/test/fake_impl_task_runner_provider.h"
@@ skipping 85 matching lines @@
   std::unique_ptr<LayerImpl> owning_layer =
       LayerImpl::Create(host_impl.active_tree(), 2);
   owning_layer->SetHasRenderSurface(true);
   ASSERT_TRUE(owning_layer->render_surface());
 
   SkXfermode::Mode blend_mode = SkXfermode::kSoftLight_Mode;
   owning_layer->SetBlendMode(blend_mode);
   RenderSurfaceImpl* render_surface = owning_layer->render_surface();
 
   root_layer->test_properties()->AddChild(std::move(owning_layer));
-  host_impl.active_tree()->SetRootLayer(std::move(root_layer));
+  host_impl.active_tree()->SetRootLayerForTesting(std::move(root_layer));
   host_impl.active_tree()->BuildLayerListAndPropertyTreesForTesting();
 
   gfx::Rect content_rect(0, 0, 50, 50);
   gfx::Rect clip_rect(5, 5, 40, 40);
   gfx::Transform origin;
   origin.Translate(30, 40);
 
   render_surface->SetContentRectForTesting(content_rect);
   render_surface->SetClipRect(clip_rect);
   render_surface->SetDrawOpacity(1.f);
@@ skipping 66 matching lines @@
   ASSERT_EQ(1u, pass_sink.RenderPasses().size());
   RenderPass* pass = pass_sink.RenderPasses()[0].get();
 
   EXPECT_EQ(RenderPassId(2, 0), pass->id);
   EXPECT_EQ(content_rect, pass->output_rect);
   EXPECT_EQ(origin, pass->transform_to_root_target);
 }
 
 }  // namespace
 }  // namespace cc