Hide Night Light behind a flag

ash/shell.cc

Index: ash/shell.cc
diff --git a/ash/shell.cc b/ash/shell.cc
index 1c72b473fa635c9caca4677b29d17a70ea5cb317..38dcd6023ef7e10b1525a6514aa435825ccb8835 100644
--- a/ash/shell.cc
+++ b/ash/shell.cc
@@ -73,7 +73,6 @@
 #include "ash/system/locale/locale_notification_controller.h"
 #include "ash/system/network/sms_observer.h"
 #include "ash/system/network/vpn_list.h"
-#include "ash/system/night_light/night_light_controller.h"
 #include "ash/system/power/power_event_observer.h"
 #include "ash/system/power/power_status.h"
 #include "ash/system/power/video_activity_notifier.h"
@@ -561,8 +560,6 @@ Shell::Shell(std::unique_ptr<ShellDelegate> shell_delegate,
       media_controller_(base::MakeUnique<MediaController>()),
       new_window_controller_(base::MakeUnique<NewWindowController>()),
       session_controller_(base::MakeUnique<SessionController>()),
-      night_light_controller_(
-          base::MakeUnique<NightLightController>(session_controller_.get())),
       shelf_controller_(base::MakeUnique<ShelfController>()),
       shell_delegate_(std::move(shell_delegate)),
       shutdown_controller_(base::MakeUnique<ShutdownController>()),
@@ -790,6 +787,11 @@ Shell::~Shell() {
 void Shell::Init(const ShellInitParams& init_params) {
   const Config config = shell_port_->GetAshConfig();
 
+  if (NightLightController::IsFeatureEnabled()) {
+    night_light_controller_ =
+        base::MakeUnique<NightLightController>(session_controller_.get());
+  }
+
   blocking_pool_ = init_params.blocking_pool;
 
   wallpaper_delegate_ = shell_delegate_->CreateWallpaperDelegate();