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

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

 // 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.
 
 #include "ash/common/system/chromeos/palette/palette_tray.h"
 
 #include "ash/common/material_design/material_design_controller.h"
 #include "ash/common/session/session_state_delegate.h"
 #include "ash/common/shelf/shelf_constants.h"
 #include "ash/common/shelf/wm_shelf.h"
@@ skipping 418 matching lines @@
       HidePalette();
     }
   }
 
   // Disable any active modes if the stylus has been inserted.
   if (stylus_state == ui::StylusState::INSERTED)
     palette_tool_manager_->DisableActiveTool(PaletteGroup::MODE);
 }
 
 void PaletteTray::OnPaletteEnabledPrefChanged(bool enabled) {
+  is_palette_enabled_ = enabled;
+
   if (!enabled) {
     SetVisible(false);
     palette_tool_manager_->DisableActiveTool(PaletteGroup::MODE);
   } else {
     UpdateIconVisibility();
   }
 }
 
 void PaletteTray::UpdateIconVisibility() {
-  SetVisible(IsInUserSession());
+  SetVisible(is_palette_enabled_ && IsInUserSession());
 }
 
 }  // namespace ash