Make sure stylus tools are always hidden if disabled by the user.

ash/common/system/chromeos/palette/palette_tray.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_SYSTEM_CHROMEOS_PALETTE_PALETTE_BUTTON_TRAY_H_
 #define ASH_COMMON_SYSTEM_CHROMEOS_PALETTE_PALETTE_BUTTON_TRAY_H_
 
 #include <map>
 #include <memory>
 
@@ skipping 106 matching lines @@
       palette_enabled_subscription_;
 
   // Weak pointer, will be parented by TrayContainer for its lifetime.
   views::ImageView* icon_;
 
   // The shelf auto-hide state is checked during the tray constructor, so we
   // have to use a helper variable instead of just checking if we have a tray
   // instance.
   bool should_block_shelf_auto_hide_ = false;
 
+  // Cached palette enabled/disabled pref value.
+  bool is_palette_enabled_ = true;
+
   // Used to indicate whether the palette bubble is automatically opened by a
   // stylus eject event.
   bool is_bubble_auto_opened_ = false;
 
   // Number of actions in pen palette bubble.
   int num_actions_in_bubble_ = 0;
 
   base::WeakPtrFactory<PaletteTray> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(PaletteTray);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SYSTEM_CHROMEOS_PALETTE_PALETTE_BUTTON_TRAY_H_