Auto open and close the palette on an eject event.

ash/common/system/chromeos/palette/eject_controller.cc

+// Copyright 2016 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/common/system/chromeos/palette/eject_controller.h"
+
+#include "ash/common/wm_shell.h"
+#include "ui/events/devices/input_device_manager.h"
+
+namespace ash {
+
+EjectController::EjectController(const OnEjectCallback& on_eject)
+    : on_eject_(on_eject) {
+  ui::InputDeviceManager::GetInstance()->AddObserver(this);
+}
+
+EjectController::~EjectController() {
+  ui::InputDeviceManager::GetInstance()->RemoveObserver(this);
+}
+
+void EjectController::OnStylusStateChanged(ui::StylusState state) {
+  on_eject_.Run(state);
+}
+
+}  // namespace ash