ui + mus: Split ContextFactory into ContextFactory(Client) and ContextFactoryPrivate

ui/aura/window_tree_host.cc

Index: ui/aura/window_tree_host.cc
diff --git a/ui/aura/window_tree_host.cc b/ui/aura/window_tree_host.cc
index 87fac84f1cfdfdd5241b829cdd23697b119055f6..f8459a471fb5e8396ad0b1874380f4bef2a58a70 100644
--- a/ui/aura/window_tree_host.cc
+++ b/ui/aura/window_tree_host.cc
@@ -254,8 +254,10 @@ void WindowTreeHost::CreateCompositor() {
   DCHECK(Env::GetInstance());
   ui::ContextFactory* context_factory = Env::GetInstance()->context_factory();
   DCHECK(context_factory);
-  compositor_.reset(
-      new ui::Compositor(context_factory, base::ThreadTaskRunnerHandle::Get()));
+  ui::ContextFactoryPrivate* context_factory_private =
+      Env::GetInstance()->context_factory_private();
+  compositor_.reset(new ui::Compositor(context_factory, context_factory_private,
+                                       base::ThreadTaskRunnerHandle::Get()));
   if (!dispatcher()) {
     window()->Init(ui::LAYER_NOT_DRAWN);
     window()->set_host(this);