[Night Light] CL2: Ash and system tray work

ash/system/tiles/tiles_default_view.cc

Index: ash/system/tiles/tiles_default_view.cc
diff --git a/ash/system/tiles/tiles_default_view.cc b/ash/system/tiles/tiles_default_view.cc
index d5c51a7eef4766fc5a4b277e7cd11d70a17242b1..9c8c725984b40680ff133b7248c16a3dfeb2a2d6 100644
--- a/ash/system/tiles/tiles_default_view.cc
+++ b/ash/system/tiles/tiles_default_view.cc
@@ -11,6 +11,7 @@
 #include "ash/shell_port.h"
 #include "ash/shutdown_controller.h"
 #include "ash/strings/grit/ash_strings.h"
+#include "ash/system/night_light/night_light_controller.h"
 #include "ash/system/tray/system_menu_button.h"
 #include "ash/system/tray/system_tray.h"
 #include "ash/system/tray/system_tray_controller.h"
@@ -41,6 +42,7 @@ TilesDefaultView::TilesDefaultView(SystemTrayItem* owner)
     : owner_(owner),
       settings_button_(nullptr),
       help_button_(nullptr),
+      night_light_button_(nullptr),
       lock_button_(nullptr),
       power_button_(nullptr) {
   DCHECK(owner_);
@@ -85,6 +87,16 @@ void TilesDefaultView::Init() {
   AddChildView(help_button_);
   AddChildView(TrayPopupUtils::CreateVerticalSeparator());
 
+  night_light_button_ =
+      new SystemMenuButton(this, TrayPopupInkDropStyle::HOST_CENTERED,
+                           Shell::Get()->night_light_controller()->enabled()
+                               ? kSystemMenuNightLightOnIcon
+                               : kSystemMenuNightLightOffIcon,
+                           IDS_ASH_STATUS_TRAY_NIGHT_LIGHT);
+  night_light_button_->SetEnabled(!disable_buttons);
+  AddChildView(night_light_button_);
+  AddChildView(TrayPopupUtils::CreateVerticalSeparator());
+
   lock_button_ =
       new SystemMenuButton(this, TrayPopupInkDropStyle::HOST_CENTERED,
                            kSystemMenuLockIcon, IDS_ASH_STATUS_TRAY_LOCK);
@@ -114,6 +126,9 @@ void TilesDefaultView::ButtonPressed(views::Button* sender,
   } else if (sender == help_button_) {
     ShellPort::Get()->RecordUserMetricsAction(UMA_TRAY_HELP);
     Shell::Get()->system_tray_controller()->ShowHelp();
+  } else if (sender == night_light_button_) {
+    ShellPort::Get()->RecordUserMetricsAction(UMA_TRAY_NIGHT_LIGHT);
+    Shell::Get()->night_light_controller()->Toggle();
   } else if (sender == lock_button_) {
     ShellPort::Get()->RecordUserMetricsAction(UMA_TRAY_LOCK_SCREEN);
     chromeos::DBusThreadManager::Get()