[Night Light] Accessibility: Make ChromeVox speak button status on toggles

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"
 #include "ash/system/tray/tray_popup_item_style.h"
+#include "ui/accessibility/ax_enums.h"
 #include "ui/accessibility/ax_node_data.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/gfx/paint_vector_icon.h"
 #include "ui/gfx/vector_icon_types.h"
 
 namespace ash {
 
 namespace {
 
 gfx::ImageSkia GetNightLightNormalStateIcon(bool night_light_enabled) {
@@ skipping 25 matching lines @@
 }  // namespace
 
 NightLightToggleButton::NightLightToggleButton(views::ButtonListener* listener)
     : SystemMenuButton(listener,
                        TrayPopupInkDropStyle::HOST_CENTERED,
                        kSystemMenuNightLightOffIcon,
                        IDS_ASH_STATUS_TRAY_NIGHT_LIGHT) {
   Update();
 }
 
+void NightLightToggleButton::Toggle() {
+  DCHECK(NightLightController::IsFeatureEnabled());
+  Shell::Get()->night_light_controller()->Toggle();
+  Update();
+  NotifyAccessibilityEvent(ui::AX_EVENT_ARIA_ATTRIBUTE_CHANGED, true);
+}
+
 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