cc : Push layer lists instead of layer tree at commit and activation

cc/layers/layer_list_iterator_unittest.cc

Index: cc/layers/layer_list_iterator_unittest.cc
diff --git a/cc/layers/layer_list_iterator_unittest.cc b/cc/layers/layer_list_iterator_unittest.cc
index 503c1e6d94a9dca3464a97413961ad44fb4c33f6..47ae72eb54ad5f876f2988950164574896ce042d 100644
--- a/cc/layers/layer_list_iterator_unittest.cc
+++ b/cc/layers/layer_list_iterator_unittest.cc
@@ -240,6 +240,7 @@ TEST(LayerListIteratorTest, VerifyTraversalOrderImpl) {
   layer1->AddChild(std::move(layer5));
 
   host_impl.active_tree()->SetRootLayer(std::move(layer1));
+  host_impl.active_tree()->BuildLayerListForTesting();
 
   int i = 1;
   for (auto* layer : *host_impl.active_tree()) {
@@ -263,6 +264,7 @@ TEST(LayerListIteratorTest, VerifySingleLayerImpl) {
   std::unique_ptr<LayerImpl> layer1 =
       LayerImpl::Create(host_impl.active_tree(), 1);
   host_impl.active_tree()->SetRootLayer(std::move(layer1));
+  host_impl.active_tree()->BuildLayerListForTesting();
 
   int i = 1;
   for (auto* layer : *host_impl.active_tree()) {
@@ -328,6 +330,7 @@ TEST(LayerListReverseIteratorTest, VerifyTraversalOrderImpl) {
   layer1->AddChild(std::move(layer5));
 
   host_impl.active_tree()->SetRootLayer(std::move(layer1));
+  host_impl.active_tree()->BuildLayerListForTesting();
 
   int i = 7;
 
@@ -353,6 +356,7 @@ TEST(LayerListReverseIteratorTest, VerifySingleLayerImpl) {
   std::unique_ptr<LayerImpl> layer1 =
       LayerImpl::Create(host_impl.active_tree(), 1);
   host_impl.active_tree()->SetRootLayer(std::move(layer1));
+  host_impl.active_tree()->BuildLayerListForTesting();
 
   int i = 1;
   for (auto* layer : base::Reversed(*host_impl.active_tree())) {