cros: Remove OS_CHROMEOS ifdefs in ash/common

ash/common/wm_root_window_controller.cc

Index: ash/common/wm_root_window_controller.cc
diff --git a/ash/common/wm_root_window_controller.cc b/ash/common/wm_root_window_controller.cc
index 77dc1570bae6fdd94776491d063efc75aecae651..f2851f6ac646bf4e8585bb61907f301b00bdac32 100644
--- a/ash/common/wm_root_window_controller.cc
+++ b/ash/common/wm_root_window_controller.cc
@@ -454,12 +454,10 @@ void WmRootWindowController::CreateContainers() {
   overlay_container->SetBoundsInScreenBehaviorForChildren(
       WmWindow::BoundsInScreenBehavior::USE_SCREEN_COORDINATES);
 
-#if defined(OS_CHROMEOS)
   WmWindow* mouse_cursor_container = CreateContainer(
       kShellWindowId_MouseCursorContainer, "MouseCursorContainer", root_);
   mouse_cursor_container->SetBoundsInScreenBehaviorForChildren(
       WmWindow::BoundsInScreenBehavior::USE_SCREEN_COORDINATES);
-#endif
 
   CreateContainer(kShellWindowId_PowerButtonAnimationContainer,
                   "PowerButtonAnimationContainer", root_);