[Night Light] CL12: String changes and fix frequent requests.

ash/system/night_light/night_light_toggle_button.cc

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/system/night_light/night_light_toggle_button.h"
 
 #include "ash/shell.h"
 #include "ash/strings/grit/ash_strings.h"
 #include "ash/system/night_light/night_light_controller.h"
 #include "ash/system/tray/tray_constants.h"
@@ skipping 18 matching lines @@
                                    TrayPopupItemStyle::ColorStyle::INACTIVE));
 }
 
 gfx::ImageSkia GetNightLightDisabledStateIcon(bool night_light_enabled) {
   return gfx::CreateVectorIcon(night_light_enabled
                                    ? kSystemMenuNightLightOnIcon
                                    : kSystemMenuNightLightOffIcon,
                                kMenuIconColorDisabled);
 }
 
+base::string16 GetNightLightTooltipText(bool night_light_enabled) {
+  return l10n_util::GetStringFUTF16(
+      IDS_ASH_STATUS_TRAY_NIGHT_LIGHT,
+      l10n_util::GetStringUTF16(
+          night_light_enabled ? IDS_ASH_STATUS_TRAY_NIGHT_LIGHT_ON_STATE
+                              : IDS_ASH_STATUS_TRAY_NIGHT_LIGHT_OFF_STATE));
+}
+
 }  // namespace
 
 NightLightToggleButton::NightLightToggleButton(views::ButtonListener* listener)
     : SystemMenuButton(listener,
                        TrayPopupInkDropStyle::HOST_CENTERED,
                        kSystemMenuNightLightOffIcon,
                        IDS_ASH_STATUS_TRAY_NIGHT_LIGHT) {
   Update();
 }
 
 void NightLightToggleButton::Update() {
   const bool night_light_enabled =
       Shell::Get()->night_light_controller()->GetEnabled();
 
+  SetTooltipText(GetNightLightTooltipText(night_light_enabled));
   SetImage(views::Button::STATE_NORMAL,
            GetNightLightNormalStateIcon(night_light_enabled));
   SetImage(views::Button::STATE_DISABLED,
            GetNightLightDisabledStateIcon(night_light_enabled));
 }
 
 void NightLightToggleButton::GetAccessibleNodeData(ui::AXNodeData* node_data) {
   node_data->SetName(
       l10n_util::GetStringUTF16(IDS_ASH_STATUS_TRAY_NIGHT_LIGHT));
   node_data->role = ui::AX_ROLE_TOGGLE_BUTTON;
   const bool is_pressed = Shell::Get()->night_light_controller()->GetEnabled();
   node_data->AddIntAttribute(
       ui::AX_ATTR_CHECKED_STATE,
       is_pressed ? ui::AX_CHECKED_STATE_TRUE : ui::AX_CHECKED_STATE_FALSE);
 }
 
 }  // namespace ash