Auto open and close the palette on an eject event.

ash/common/palette_delegate.h

 // 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.
 
 #ifndef ASH_COMMON_PALETTE_DELEGATE_H_
 #define ASH_COMMON_PALETTE_DELEGATE_H_
 
 #include "ash/ash_export.h"
+#include "base/callback.h"
 #include "base/macros.h"
+#include "ui/events/devices/stylus_state.h"
 
 namespace ash {
 
 // This delegate allows the UI code in ash, e.g. |PaletteTray|, to perform
 // Chrome-specific actions.
 class PaletteDelegate {
  public:
+  using OnStylusStateChangedCallback = base::Callback<void(ui::StylusState)>;
+
   virtual ~PaletteDelegate() {}
 
   // Create a new note.
   virtual void CreateNote() = 0;
 
   // Returns true if there is a note-taking application available.
   virtual bool HasNoteApp() = 0;
 
   // Enables or disables the partial magnifier.
   virtual void SetPartialMagnifierState(bool enabled) = 0;
 
+  // Set callback that is run when a stylus is inserted or removed.
+  virtual void SetStylusStateChangedCallback(
+      const OnStylusStateChangedCallback& on_stylus_state_changed) = 0;
+
+  // Returns true if the palette should be automatically opened on an eject
+  // event.
+  virtual bool ShouldAutoOpenPalette() = 0;
+
   // Take a screenshot of the entire window.
   virtual void TakeScreenshot() = 0;
 
   // Take a screenshot of a user-selected region.
   virtual void TakePartialScreenshot() = 0;
 
  private:
   DISALLOW_ASSIGN(PaletteDelegate);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_PALETTE_DELEGATE_H_