cros: Fix clusterfuzz crash opening stylus palette

ash/common/accelerators/accelerator_controller.cc

 // Copyright (c) 2012 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/accelerators/accelerator_controller.h"
 
 #include <utility>
 
 #include "ash/common/accelerators/accelerator_commands.h"
 #include "ash/common/accelerators/accelerator_controller_delegate.h"
@@ skipping 496 matching lines @@
 void HandleLock() {
   base::RecordAction(UserMetricsAction("Accel_LockScreen_L"));
   WmShell::Get()->GetSessionStateDelegate()->LockScreen();
 }
 
 void HandleShowStylusTools() {
   base::RecordAction(UserMetricsAction("Accel_Show_Stylus_Tools"));
 
   RootWindowController* root_window_controller =
       Shell::GetWmRootWindowForNewWindows()->GetRootWindowController();
-  PaletteTray* palette_tray =
-      root_window_controller->GetShelf()->GetStatusAreaWidget()->palette_tray();
-  palette_tray->ShowPalette();
+  StatusAreaWidget* status_area_widget =
+      root_window_controller->GetShelf()->GetStatusAreaWidget();
+  // Tests (clusterfuzz) can trigger this before the status area is ready.
+  if (status_area_widget)
+    status_area_widget->palette_tray()->ShowPalette();
 }
 
 bool CanHandleShowStylusTools() {
   return Shell::GetInstance()->palette_delegate() &&
          Shell::GetInstance()->palette_delegate()->ShouldShowPalette();
 }
 
 void HandleSuspend() {
   base::RecordAction(UserMetricsAction("Accel_Suspend"));
   chromeos::DBusThreadManager::Get()->GetPowerManagerClient()->RequestSuspend();
@@ skipping 761 matching lines @@
       data->uma_histogram_name, data->notification_message_id,
       data->old_shortcut_id, data->new_shortcut_id);
 
   if (!data->deprecated_enabled)
     return AcceleratorProcessingStatus::STOP;
 
   return AcceleratorProcessingStatus::PROCEED;
 }
 
 }  // namespace ash