Replace LayerImpl::sorting_context_id with transform reference.

cc/trees/layer_tree_impl_unittest.cc

Index: cc/trees/layer_tree_impl_unittest.cc
diff --git a/cc/trees/layer_tree_impl_unittest.cc b/cc/trees/layer_tree_impl_unittest.cc
index 16e3d91f259111281b4790c34a1928ecdd81479e..8b33f9092f040fb36226b0602f8efabff94beaa2 100644
--- a/cc/trees/layer_tree_impl_unittest.cc
+++ b/cc/trees/layer_tree_impl_unittest.cc
@@ -80,26 +80,28 @@ class LayerTreeImplTest : public testing::Test {
       gfx::Transform translate_z;
       translate_z.Translate3d(0, 0, root_depth);
       root->test_properties()->transform = translate_z;
+      root->test_properties()->sorting_context_id = root_sorting_context;
       root->SetBounds(bounds);
       root->SetDrawsContent(true);
-      root->Set3dSortingContextId(root_sorting_context);
     }
     {
       gfx::Transform translate_z;
       translate_z.Translate3d(0, 0, left_child_depth);
       left_child->test_properties()->transform = translate_z;
+      left_child->test_properties()->sorting_context_id =
+          left_child_sorting_context;
       left_child->SetBounds(bounds);
       left_child->SetDrawsContent(true);
-      left_child->Set3dSortingContextId(left_child_sorting_context);
       left_child->test_properties()->should_flatten_transform = false;
     }
     {
       gfx::Transform translate_z;
       translate_z.Translate3d(0, 0, right_child_depth);
       right_child->test_properties()->transform = translate_z;
+      right_child->test_properties()->sorting_context_id =
+          right_child_sorting_context;
       right_child->SetBounds(bounds);
       right_child->SetDrawsContent(true);
-      right_child->Set3dSortingContextId(right_child_sorting_context);
     }
 
     root->test_properties()->AddChild(std::move(left_child));
@@ -941,7 +943,7 @@ TEST_F(LayerTreeImplTest, HitTestingForMultipleLayersAtVaryingDepths) {
   root->SetBounds(gfx::Size(100, 100));
   root->SetDrawsContent(true);
   root->test_properties()->should_flatten_transform = false;
-  root->Set3dSortingContextId(1);
+  root->test_properties()->sorting_context_id = 1;
   {
     // child 1 and child2 are initialized to overlap between x=50 and x=60.
     // grand_child is set to overlap both child1 and child2 between y=50 and
@@ -960,7 +962,7 @@ TEST_F(LayerTreeImplTest, HitTestingForMultipleLayersAtVaryingDepths) {
     child1->SetBounds(gfx::Size(50, 50));
     child1->SetDrawsContent(true);
     child1->test_properties()->should_flatten_transform = false;
-    child1->Set3dSortingContextId(1);
+    child1->test_properties()->sorting_context_id = 1;
 
     child2->SetPosition(gfx::PointF(50.f, 10.f));
     child2->SetBounds(gfx::Size(50, 50));
@@ -969,7 +971,7 @@ TEST_F(LayerTreeImplTest, HitTestingForMultipleLayersAtVaryingDepths) {
     child2->test_properties()->transform = translate_z;
     child2->SetDrawsContent(true);
     child2->test_properties()->should_flatten_transform = false;
-    child2->Set3dSortingContextId(1);
+    child2->test_properties()->sorting_context_id = 1;
 
     // Remember that grand_child is positioned with respect to its parent (i.e.
     // child1).  In screen space, the intended position is (10, 50), with size