Transfer LayerImpl ownership to LayerTreeImpl

cc/test/fake_layer_tree_host.cc

 // Copyright 2013 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/test/fake_layer_tree_host.h"
 
 #include "cc/layers/layer.h"
 #include "cc/test/fake_image_serialization_processor.h"
 #include "cc/test/test_task_graph_runner.h"
 
@@ skipping 63 matching lines @@
 
 const RendererCapabilities& FakeLayerTreeHost::GetRendererCapabilities() const {
   if (renderer_capabilities_set)
     return renderer_capabilities;
   return LayerTreeHost::GetRendererCapabilities();
 }
 
 void FakeLayerTreeHost::SetNeedsCommit() { needs_commit_ = true; }
 
 LayerImpl* FakeLayerTreeHost::CommitAndCreateLayerImplTree() {
-  scoped_ptr<LayerImpl> old_root_layer_impl = active_tree()->DetachLayerTree();
-
-  scoped_ptr<LayerImpl> layer_impl = TreeSynchronizer::SynchronizeTrees(
-      root_layer(), std::move(old_root_layer_impl), active_tree());
+  TreeSynchronizer::SynchronizeTrees(root_layer(), active_tree());
   active_tree()->SetPropertyTrees(*property_trees());
   TreeSynchronizer::PushLayerProperties(root_layer()->layer_tree_host(),
                                         active_tree());
 
-  active_tree()->SetRootLayer(std::move(layer_impl));
   active_tree()->UpdatePropertyTreeScrollOffset(property_trees());
 
   if (page_scale_layer() && inner_viewport_scroll_layer()) {
     active_tree()->SetViewportLayersFromIds(
         overscroll_elasticity_layer() ? overscroll_elasticity_layer()->id()
                                       : Layer::INVALID_ID,
         page_scale_layer()->id(), inner_viewport_scroll_layer()->id(),
         outer_viewport_scroll_layer() ? outer_viewport_scroll_layer()->id()
                                       : Layer::INVALID_ID);
   }
 
   active_tree()->UpdatePropertyTreesForBoundsDelta();
   return active_tree()->root_layer();
 }
 
 LayerImpl* FakeLayerTreeHost::CommitAndCreatePendingTree() {
-  scoped_ptr<LayerImpl> old_root_layer_impl = pending_tree()->DetachLayerTree();
-
-  scoped_ptr<LayerImpl> layer_impl = TreeSynchronizer::SynchronizeTrees(
-      root_layer(), std::move(old_root_layer_impl), pending_tree());
+  TreeSynchronizer::SynchronizeTrees(root_layer(), pending_tree());
   pending_tree()->SetPropertyTrees(*property_trees());
   TreeSynchronizer::PushLayerProperties(root_layer()->layer_tree_host(),
                                         pending_tree());
-
-  pending_tree()->SetRootLayer(std::move(layer_impl));
   pending_tree()->UpdatePropertyTreeScrollOffset(property_trees());
   return pending_tree()->root_layer();
 }
 
 }  // namespace cc