Auto open and close the palette on an eject event.

ash/common/system/chromeos/palette/palette_tray.h

Index: ash/common/system/chromeos/palette/palette_tray.h
diff --git a/ash/common/system/chromeos/palette/palette_tray.h b/ash/common/system/chromeos/palette/palette_tray.h
index 18d900ab1bc31f3f6a8337343b9d0a6aa7f2578b..46b8932a8de47bf7c2f6d77b21fe039ece5cd4d4 100644
--- a/ash/common/system/chromeos/palette/palette_tray.h
+++ b/ash/common/system/chromeos/palette/palette_tray.h
@@ -22,6 +22,7 @@ class Widget;
 
 namespace ash {
 
+class EjectController;
 class TrayBubbleWrapper;
 class PaletteToolManager;
 
@@ -82,12 +83,18 @@ class ASH_EXPORT PaletteTray : public TrayBackgroundView,
   // Sets the icon to visible if the palette can be used.
   void UpdateIconVisibility();
 
+  // Called when a pointer eject event is received. If |ejected| is true, the
+  // pointer was removed. If false, the pointer was inserted.
+  void OnEject(bool ejected);
+
   bool OpenBubble();
   void AddToolsToView(views::View* host);
 
   std::unique_ptr<PaletteToolManager> palette_tool_manager_;
   std::unique_ptr<TrayBubbleWrapper> bubble_;
 
+  std::unique_ptr<EjectController> eject_controller_;
+
   // Weak pointer, will be parented by TrayContainer for its lifetime.
   views::ImageView* icon_;