cros: Fix clusterfuzz crash opening stylus palette

ash/common/accelerators/accelerator_controller.cc

Index: ash/common/accelerators/accelerator_controller.cc
diff --git a/ash/common/accelerators/accelerator_controller.cc b/ash/common/accelerators/accelerator_controller.cc
index 50fbb48d468a73e876cba08301e08e457cd1a19b..ac5cf4645bd28095a921209b3240fbee54cd886f 100644
--- a/ash/common/accelerators/accelerator_controller.cc
+++ b/ash/common/accelerators/accelerator_controller.cc
@@ -514,9 +514,11 @@ void HandleShowStylusTools() {
 
   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() {