Revert of Improves focus/activation for aura-mus and DesktopNativeWidgetAura

ui/views/mus/mus_client.h

Index: ui/views/mus/mus_client.h
diff --git a/ui/views/mus/mus_client.h b/ui/views/mus/mus_client.h
index e94dea2f8ba0cc9004eaade29231d8040ec651e8..4092d1284298a0fec4a8549ddcafac057ebff0d5 100644
--- a/ui/views/mus/mus_client.h
+++ b/ui/views/mus/mus_client.h
@@ -32,6 +32,7 @@
 }
 
 namespace wm {
+class FocusController;
 class WMState;
 }
 
@@ -90,6 +91,7 @@
   void OnEmbedRootDestroyed(aura::Window* root) override;
   void OnPointerEventObserved(const ui::PointerEvent& event,
                               aura::Window* target) override;
+  aura::client::FocusClient* GetFocusClient() override;
   aura::client::CaptureClient* GetCaptureClient() override;
   aura::PropertyConverter* GetPropertyConverter() override;
 
@@ -110,6 +112,8 @@
 
   std::unique_ptr<ScreenMus> screen_;
 
+  std::unique_ptr<wm::FocusController> focus_controller_;
+
   std::unique_ptr<aura::PropertyConverter> property_converter_;
 
   std::unique_ptr<aura::WindowTreeClient> window_tree_client_;