Converts ShellObserver from aura::Window to ash::WmWindow

ash/high_contrast/high_contrast_controller.cc

Index: ash/high_contrast/high_contrast_controller.cc
diff --git a/ash/high_contrast/high_contrast_controller.cc b/ash/high_contrast/high_contrast_controller.cc
index 418dd7162c1768bcd4b66a478039e4d6611b8bee..27e2eab8bb984c7fba2e07021680d1befa9abf7f 100644
--- a/ash/high_contrast/high_contrast_controller.cc
+++ b/ash/high_contrast/high_contrast_controller.cc
@@ -4,6 +4,7 @@
 
 #include "ash/high_contrast/high_contrast_controller.h"
 
+#include "ash/aura/wm_window_aura.h"
 #include "ash/shell.h"
 #include "ui/aura/window_event_dispatcher.h"
 #include "ui/compositor/layer.h"
@@ -34,8 +35,8 @@ void HighContrastController::UpdateDisplay(aura::Window* root_window) {
   root_window->layer()->SetLayerInverted(enabled_);
 }
 
-void HighContrastController::OnRootWindowAdded(aura::Window* root_window) {
-  UpdateDisplay(root_window);
+void HighContrastController::OnRootWindowAdded(WmWindow* root_window) {
+  UpdateDisplay(WmWindowAura::GetAuraWindow(root_window));
 }
 
 }  // namespace ash