platform-window: Add a PlatformWindowFactory for creating windows.

ui/aura/window_tree_host_ozone.cc

Index: ui/aura/window_tree_host_ozone.cc
diff --git a/ui/aura/window_tree_host_ozone.cc b/ui/aura/window_tree_host_ozone.cc
index 0dd8084bb46e7c6cebec40fd1ee0a5b97e80bd8b..d234d317f8a2fb2f93e5001baf93a5e494dfeeb0 100644
--- a/ui/aura/window_tree_host_ozone.cc
+++ b/ui/aura/window_tree_host_ozone.cc
@@ -7,15 +7,15 @@
 #include "ui/aura/window_event_dispatcher.h"
 #include "ui/ozone/public/cursor_factory_ozone.h"
 #include "ui/ozone/public/event_factory_ozone.h"
-#include "ui/ozone/public/ozone_platform.h"
-#include "ui/platform_window/platform_window.h"
+#include "ui/platform_window/platform_window_factory.h"
+#include "ui/platform_window/types/platform_window.h"
 
 namespace aura {
 
 WindowTreeHostOzone::WindowTreeHostOzone(const gfx::Rect& bounds)
-    : widget_(gfx::kNullAcceleratedWidget) {
-  platform_window_ =
-      ui::OzonePlatform::GetInstance()->CreatePlatformWindow(this, bounds);
+    : widget_(gfx::kNullAcceleratedWidget),
+      platform_window_(ui::PlatformWindowFactory::GetInstance()
+                           ->CreatePlatformWindow(this, bounds)) {
 }
 
 WindowTreeHostOzone::~WindowTreeHostOzone() {