Hide ash palette on lock screen, show it in guest mode.

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 27 matching lines @@
  public:
   explicit PaletteTray(WmShelf* wm_shelf);
   ~PaletteTray() override;
 
   // ActionableView:
   bool PerformAction(const ui::Event& event) override;
 
   // SessionStateObserver:
   void SessionStateChanged(SessionStateDelegate::SessionState state) override;
 
+  // ShellObserver:
+  void OnLockStateChanged(bool locked) override;
+
   // TrayBackgroundView:
   void ClickedOutsideBubble() override;
   base::string16 GetAccessibleNameForTray() override;
   void HideBubbleWithView(const views::TrayBubbleView* bubble_view) override;
   void SetShelfAlignment(ShelfAlignment alignment) override;
   void AnchorUpdated() override;
 
   // PaletteToolManager::Delegate:
   void HidePalette() override;
 
@@ skipping 50 matching lines @@
   views::ImageView* icon_;
 
   base::WeakPtrFactory<PaletteTray> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(PaletteTray);
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_SYSTEM_CHROMEOS_PALETTE_PALETTE_BUTTON_TRAY_H_