Auto open and close the palette on an eject event.

chrome/browser/ui/ash/palette_delegate_chromeos.h

 // Copyright 2015 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.
 
 #ifndef CHROME_BROWSER_UI_ASH_PALETTE_DELEGATE_CHROMEOS_H_
 #define CHROME_BROWSER_UI_ASH_PALETTE_DELEGATE_CHROMEOS_H_
 
 #include <string>
 
 #include "ash/common/palette_delegate.h"
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/values.h"
+#include "ui/events/devices/input_device_event_observer.h"
 
 namespace chromeos {
 
 // A class which allows the Ash palette to perform chrome actions.
-class PaletteDelegateChromeOS : public ash::PaletteDelegate {
+class PaletteDelegateChromeOS : public ash::PaletteDelegate,
+                                public ui::InputDeviceEventObserver {
  public:
   PaletteDelegateChromeOS();
   ~PaletteDelegateChromeOS() override;
 
  private:
   // ash::PaletteDelegate:
   void CreateNote() override;
   bool HasNoteApp() override;
   void SetPartialMagnifierState(bool enabled) override;
+  void SetStylusStateChangedCallback(
+      const OnStylusStateChangedCallback& on_stylus_state_changed) override;
+  bool ShouldAutoOpenPalette() override;
   void TakeScreenshot() override;
   void TakePartialScreenshot() override;
 
+  // ui::InputDeviceObserver:
+  void OnStylusStateChanged(ui::StylusState state) override;
+
+  OnStylusStateChangedCallback on_stylus_state_changed_;
+
   DISALLOW_COPY_AND_ASSIGN(PaletteDelegateChromeOS);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_UI_ASH_PALETTE_DELEGATE_CHROMEOS_H_