Use correct theme for the off icon of NightLight, fix tooltip and a11y

ash/system/night_light/night_light_toggle_button.cc

Index: ash/system/night_light/night_light_toggle_button.cc
diff --git a/ash/system/night_light/night_light_toggle_button.cc b/ash/system/night_light/night_light_toggle_button.cc
new file mode 100644
index 0000000000000000000000000000000000000000..ca3eb6e9ea49ad6d0df04011b73b326299f8766d
--- /dev/null
+++ b/ash/system/night_light/night_light_toggle_button.cc
@@ -0,0 +1,67 @@
+// 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_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) {
+  if (night_light_enabled)
+    return gfx::CreateVectorIcon(kSystemMenuNightLightOnIcon, kMenuIconColor);
+
+  // Use the same icon theme used for inactive items in the tray when
+  // NightLight is not active.
+  return gfx::CreateVectorIcon(kSystemMenuNightLightOffIcon,
+                               TrayPopupItemStyle::GetIconColor(
+                                   TrayPopupItemStyle::ColorStyle::INACTIVE));
+}
+
+gfx::ImageSkia GetNightLightDisabledStateIcon(bool night_light_enabled) {
+  return gfx::CreateVectorIcon(night_light_enabled
+                                   ? kSystemMenuNightLightOnIcon
+                                   : kSystemMenuNightLightOffIcon,
+                               kMenuIconColorDisabled);
+}
+
+}  // 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();
+
+  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;
+  if (Shell::Get()->night_light_controller()->GetEnabled())
+    node_data->AddState(ui::AX_STATE_PRESSED);
+}
+
+}  // namespace ash