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

ui/views/test/views_test_helper_aura.h

Index: ui/views/test/views_test_helper_aura.h
diff --git a/ui/views/test/views_test_helper_aura.h b/ui/views/test/views_test_helper_aura.h
index 8ec540f90bd92ce52335ed43423a826710cba5a9..158c3ac9786c29361df9c9216ed90d362d8e5e22 100644
--- a/ui/views/test/views_test_helper_aura.h
+++ b/ui/views/test/views_test_helper_aura.h
@@ -31,7 +31,8 @@ namespace views {
 class ViewsTestHelperAura : public ViewsTestHelper {
  public:
   ViewsTestHelperAura(base::MessageLoopForUI* message_loop,
-                      ui::ContextFactory* context_factory);
+                      ui::ContextFactory* context_factory,
+                      ui::ContextFactoryPrivate* context_factory_private);
   ~ViewsTestHelperAura() override;
 
   void EnableMusWithWindowTreeClient(
@@ -44,6 +45,7 @@ class ViewsTestHelperAura : public ViewsTestHelper {
 
  private:
   ui::ContextFactory* context_factory_;
+  ui::ContextFactoryPrivate* context_factory_private_;
   std::unique_ptr<aura::test::AuraTestHelper> aura_test_helper_;
   std::unique_ptr<aura::client::ScreenPositionClient> screen_position_client_;