Auto open and close the palette on an eject event.

chrome/browser/ui/ash/palette_delegate_chromeos.h

Index: chrome/browser/ui/ash/palette_delegate_chromeos.h
diff --git a/chrome/browser/ui/ash/palette_delegate_chromeos.h b/chrome/browser/ui/ash/palette_delegate_chromeos.h
index 51e638e6a91ed43ce9b48fba1c19ad0d9552cb1e..78cc1b718a5c071802e5eb1dd961f3f801c66205 100644
--- a/chrome/browser/ui/ash/palette_delegate_chromeos.h
+++ b/chrome/browser/ui/ash/palette_delegate_chromeos.h
@@ -11,11 +11,13 @@
 #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;
@@ -25,9 +27,17 @@ class PaletteDelegateChromeOS : public 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);
 };