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 e4053151b0ebd0ba969701b160ebb8b42816c2a6..82616060a551b7f100ad8e691b3fd24a00bde4a4 100644
--- a/ui/aura/window_tree_host.cc
+++ b/ui/aura/window_tree_host.cc
@@ -249,8 +249,10 @@ 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);