cc: Move data to LayerTree from LayerTreeHost.

cc/test/layer_tree_pixel_test.cc

Index: cc/test/layer_tree_pixel_test.cc
diff --git a/cc/test/layer_tree_pixel_test.cc b/cc/test/layer_tree_pixel_test.cc
index 9ac636256feb3ee379dc68b7fefa58894ddf6169..3ac18fcbcb7f396e8be30333e4d6cd1da75a0c1f 100644
--- a/cc/test/layer_tree_pixel_test.cc
+++ b/cc/test/layer_tree_pixel_test.cc
@@ -105,8 +105,8 @@ void LayerTreePixelTest::ReadbackResult(
 }
 
 void LayerTreePixelTest::BeginTest() {
-  Layer* target = readback_target_ ? readback_target_
-                                   : layer_tree_host()->root_layer();
+  Layer* target =
+      readback_target_ ? readback_target_ : layer_tree()->root_layer();
   target->RequestCopyOfOutput(CreateCopyOutputRequest());
   PostSetNeedsCommitToMainThread();
 }
@@ -219,7 +219,7 @@ void LayerTreePixelTest::SetupTree() {
   scoped_refptr<Layer> root = Layer::Create();
   root->SetBounds(content_root_->bounds());
   root->AddChild(content_root_);
-  layer_tree_host()->SetRootLayer(root);
+  layer_tree()->SetRootLayer(root);
   LayerTreeTest::SetupTree();
 }