Change FocusSynchronizer to maintain active focus client and window.

ui/aura/client/focus_client.cc

Index: ui/aura/client/focus_client.cc
diff --git a/ui/aura/client/focus_client.cc b/ui/aura/client/focus_client.cc
index 0a916422e40d2b074613b40a1cecfbfac4da11ff..03ff97a63a6a1a29ad42ba64fc886caf1da51488 100644
--- a/ui/aura/client/focus_client.cc
+++ b/ui/aura/client/focus_client.cc
@@ -4,16 +4,13 @@
 
 #include "ui/aura/client/focus_client.h"
 
+#include "ui/aura/client/aura_constants.h"
 #include "ui/aura/window_event_dispatcher.h"
 #include "ui/base/class_property.h"
 
-DECLARE_EXPORTED_UI_CLASS_PROPERTY_TYPE(AURA_EXPORT, aura::client::FocusClient*)
-
 namespace aura {
 namespace client {
 
-DEFINE_UI_CLASS_PROPERTY_KEY(FocusClient*, kFocusClientKey, nullptr);
-
 void SetFocusClient(Window* root_window, FocusClient* client) {
   DCHECK_EQ(root_window->GetRootWindow(), root_window);
   root_window->SetProperty(kFocusClientKey, client);