Replace LayerImpl::sorting_context_id with transform reference.

cc/layers/picture_layer_unittest.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/layers/picture_layer.h"
 
 #include <stddef.h>
 
 #include "base/memory/ptr_util.h"
 #include "base/threading/thread_task_runner_handle.h"
@@ skipping 215 matching lines @@
   layer->SetBounds(gfx::Size(11, 11));
   layer->SavePaintProperties();
 
   host_impl.CreatePendingTree();
   layer_impl = static_cast<FakePictureLayerImpl*>(
       host_impl.pending_tree()->root_layer_for_testing());
 
   // We should now have invalid contents and should therefore clear the
   // recording source.
   layer->PushPropertiesTo(layer_impl);
+  host_impl.pending_tree()->BuildPropertyTreesForTesting();
 
   host_impl.ActivateSyncTree();
 
   std::unique_ptr<RenderPass> render_pass = RenderPass::Create();
   AppendQuadsData data;
   host_impl.active_tree()->root_layer_for_testing()->WillDraw(
       DRAW_MODE_SOFTWARE, nullptr);
   host_impl.active_tree()->root_layer_for_testing()->AppendQuads(
       render_pass.get(), &data);
   host_impl.active_tree()->root_layer_for_testing()->DidDraw(nullptr);
@@ skipping 112 matching lines @@
   host2->Composite(base::TimeTicks::Now());
   EXPECT_EQ(3, layer->update_count());
   EXPECT_EQ(1, host2->SourceFrameNumber());
 
   animation_host->SetMutatorHostClient(nullptr);
   animation_host2->SetMutatorHostClient(nullptr);
 }
 
 }  // namespace
 }  // namespace cc