cc: Clean up root_layer code in LTI

cc/layers/picture_layer_impl_perftest.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/picture_layer_impl.h"
 
 #include "base/macros.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "cc/debug/lap_timer.h"
 #include "cc/test/fake_impl_task_runner_provider.h"
@@ skipping 50 matching lines @@
         FakeRasterSource::CreateFilled(layer_bounds);
     host_impl_.CreatePendingTree();
     LayerTreeImpl* pending_tree = host_impl_.pending_tree();
     pending_tree->DetachLayers();
 
     std::unique_ptr<FakePictureLayerImpl> pending_layer =
         FakePictureLayerImpl::CreateWithRasterSource(pending_tree, 7,
                                                      raster_source);
     pending_layer->SetDrawsContent(true);
     pending_layer->test_properties()->force_render_surface = true;
-    pending_tree->SetRootLayer(std::move(pending_layer));
+    pending_tree->SetRootLayerForTesting(std::move(pending_layer));
     pending_tree->BuildLayerListAndPropertyTreesForTesting();
 
     pending_layer_ = static_cast<FakePictureLayerImpl*>(
         host_impl_.pending_tree()->LayerById(7));
   }
 
   void RunRasterQueueConstructAndIterateTest(const std::string& test_name,
                                              int num_tiles,
                                              const gfx::Size& viewport_size) {
     host_impl_.SetViewportSize(viewport_size);
@@ skipping 175 matching lines @@
   ASSERT_TRUE(host_impl_.tile_manager() != nullptr);
   host_impl_.tile_manager()->InitializeTilesWithResourcesForTesting(all_tiles);
 
   RunEvictionQueueConstructTest("0_0_100x100", gfx::Rect(0, 0, 100, 100));
   RunEvictionQueueConstructTest("5000_0_100x100", gfx::Rect(5000, 0, 100, 100));
   RunEvictionQueueConstructTest("9999_0_100x100", gfx::Rect(9999, 0, 100, 100));
 }
 
 }  // namespace
 }  // namespace cc