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

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/shelf/shelf_constants.h"
 #include "ash/common/shelf/wm_shelf.h"
 #include "ash/common/shelf/wm_shelf_util.h"
 #include "ash/common/shell_window_ids.h"
@@ skipping 206 matching lines @@
 
     host->AddChildView(view.view);
   }
 }
 
 void PaletteTray::SessionStateChanged(
     SessionStateDelegate::SessionState state) {
   UpdateIconVisibility();
 }
 
+void PaletteTray::OnLockStateChanged(bool locked) {
+  UpdateIconVisibility();
+}
+
 void PaletteTray::ClickedOutsideBubble() {
   bubble_.reset();
 }
 
 base::string16 PaletteTray::GetAccessibleNameForTray() {
   return l10n_util::GetStringUTF16(IDS_ASH_STYLUS_TOOLS_TITLE);
 }
 
 void PaletteTray::HideBubbleWithView(const views::TrayBubbleView* bubble_view) {
   if (bubble_->bubble_view() == bubble_view)
@@ skipping 115 matching lines @@
       WmShell::Get()->GetSessionStateDelegate();
 
   SetVisible(!session_state_delegate->IsScreenLocked() &&
              session_state_delegate->GetSessionState() ==
                  SessionStateDelegate::SESSION_STATE_ACTIVE &&
              WmShell::Get()->system_tray_delegate()->GetUserLoginStatus() !=
                  LoginStatus::KIOSK_APP);
 }
 
 }  // namespace ash