Refactor and push window properties up to class properties.

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 a5f179df589ac441a52da6208de0364f36aa1081..7da5011e329937993aa20725aa6af4c2356006cd 100644
--- a/ui/aura/client/focus_client.cc
+++ b/ui/aura/client/focus_client.cc
@@ -5,14 +5,14 @@
 #include "ui/aura/client/focus_client.h"
 
 #include "ui/aura/window_event_dispatcher.h"
-#include "ui/aura/window_property.h"
+#include "ui/base/class_property.h"
 
-DECLARE_EXPORTED_WINDOW_PROPERTY_TYPE(AURA_EXPORT, aura::client::FocusClient*)
+DECLARE_EXPORTED_CLASS_PROPERTY_TYPE(AURA_EXPORT, aura::client::FocusClient*)
 
 namespace aura {
 namespace client {
 
-DEFINE_WINDOW_PROPERTY_KEY(FocusClient*, kFocusClientKey, nullptr);
+DEFINE_CLASS_PROPERTY_KEY(FocusClient*, kFocusClientKey, nullptr);
 
 void SetFocusClient(Window* root_window, FocusClient* client) {
   DCHECK_EQ(root_window->GetRootWindow(), root_window);