Replace LayerImpl::sorting_context_id with transform reference.

cc/layers/layer.cc

 // Copyright 2010 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.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 1147 matching lines @@
   layer->SetTouchEventHandlerRegion(inputs_.touch_event_handler_region);
   layer->SetContentsOpaque(inputs_.contents_opaque);
   layer->SetPosition(inputs_.position);
   layer->set_should_flatten_transform_from_property_tree(
       should_flatten_transform_from_property_tree_);
   layer->set_draw_blend_mode(draw_blend_mode_);
   layer->SetUseParentBackfaceVisibility(inputs_.use_parent_backface_visibility);
   layer->SetUseLocalTransformForBackfaceVisibility(
       use_local_transform_for_backface_visibility_);
   layer->SetShouldCheckBackfaceVisibility(should_check_backface_visibility_);
-  layer->Set3dSortingContextId(inputs_.sorting_context_id);
 
   layer->SetScrollClipLayer(inputs_.scroll_clip_layer_id);
   layer->set_user_scrollable_horizontal(inputs_.user_scrollable_horizontal);
   layer->set_user_scrollable_vertical(inputs_.user_scrollable_vertical);
   layer->SetElementId(inputs_.element_id);
   layer->SetMutableProperties(inputs_.mutable_properties);
 
   // When a scroll offset animation is interrupted the new scroll position on
   // the pending tree will clobber any impl-side scrolling occuring on the
   // active tree. To do so, avoid scrolling the pending tree along with it
@@ skipping 485 matching lines @@
 
 LayerTree* Layer::GetLayerTree() const {
   return layer_tree_;
 }
 
 void Layer::SetLayerIdForTesting(int id) {
   inputs_.layer_id = id;
 }
 
 }  // namespace cc