Setup LayerTree class, refactor 2 functions from LayerTreeHost to it.

cc/trees/tree_synchronizer_unittest.cc

Index: cc/trees/tree_synchronizer_unittest.cc
diff --git a/cc/trees/tree_synchronizer_unittest.cc b/cc/trees/tree_synchronizer_unittest.cc
index 8090415b7a5505bc32a6f935f5546a07b6a275cc..1041c7983570443ab1d069f410c6e926d95e3601 100644
--- a/cc/trees/tree_synchronizer_unittest.cc
+++ b/cc/trees/tree_synchronizer_unittest.cc
@@ -217,7 +217,7 @@ TEST_F(TreeSynchronizerTest, SyncSimpleTreeReusingLayers) {
                           host_->active_tree());
 
   // We have to push properties to pick up the destruction list pointer.
-  TreeSynchronizer::PushLayerProperties(layer_tree_root->layer_tree_host(),
+  TreeSynchronizer::PushLayerProperties(layer_tree_root->GetLayerTree(),
                                         host_->active_tree());
 
   // Add a new layer to the Layer side
@@ -266,7 +266,7 @@ TEST_F(TreeSynchronizerTest, SyncSimpleTreeAndTrackStackingOrderChange) {
                           host_->active_tree());
 
   // We have to push properties to pick up the destruction list pointer.
-  TreeSynchronizer::PushLayerProperties(layer_tree_root->layer_tree_host(),
+  TreeSynchronizer::PushLayerProperties(layer_tree_root->GetLayerTree(),
                                         host_->active_tree());
 
   host_->active_tree()->ResetAllChangeTracking();
@@ -280,7 +280,7 @@ TEST_F(TreeSynchronizerTest, SyncSimpleTreeAndTrackStackingOrderChange) {
   ExpectTreesAreIdentical(layer_tree_root.get(), layer_impl_tree_root,
                           host_->active_tree());
 
-  TreeSynchronizer::PushLayerProperties(layer_tree_root->layer_tree_host(),
+  TreeSynchronizer::PushLayerProperties(layer_tree_root->GetLayerTree(),
                                         host_->active_tree());
 
   // Check that the impl thread properly tracked the change.
@@ -316,7 +316,7 @@ TEST_F(TreeSynchronizerTest, SyncSimpleTreeAndProperties) {
   ExpectTreesAreIdentical(layer_tree_root.get(), layer_impl_tree_root,
                           host_->active_tree());
 
-  TreeSynchronizer::PushLayerProperties(layer_tree_root->layer_tree_host(),
+  TreeSynchronizer::PushLayerProperties(layer_tree_root->GetLayerTree(),
                                         host_->active_tree());
 
   // Check that the property values we set on the Layer tree are reflected in
@@ -366,7 +366,7 @@ TEST_F(TreeSynchronizerTest, ReuseLayerImplsAfterStructuralChange) {
                           host_->active_tree());
 
   // We have to push properties to pick up the destruction list pointer.
-  TreeSynchronizer::PushLayerProperties(layer_tree_root->layer_tree_host(),
+  TreeSynchronizer::PushLayerProperties(layer_tree_root->GetLayerTree(),
                                         host_->active_tree());
 
   // Now restructure the tree to look like this:
@@ -422,7 +422,7 @@ TEST_F(TreeSynchronizerTest, SyncSimpleTreeThenDestroy) {
                           host_->active_tree());
 
   // We have to push properties to pick up the destruction list pointer.
-  TreeSynchronizer::PushLayerProperties(old_layer_tree_root->layer_tree_host(),
+  TreeSynchronizer::PushLayerProperties(old_layer_tree_root->GetLayerTree(),
                                         host_->active_tree());
 
   // Remove all children on the Layer side.