cros: AutomationManagerAura::SendEvent crash fix

chrome/browser/ui/aura/accessibility/automation_manager_aura.cc

Index: chrome/browser/ui/aura/accessibility/automation_manager_aura.cc
diff --git a/chrome/browser/ui/aura/accessibility/automation_manager_aura.cc b/chrome/browser/ui/aura/accessibility/automation_manager_aura.cc
index a687ecb2fff448a30580103ede5ad53d071c17bb..658012d2832988eae1ce7ea71a9ef32547901417 100644
--- a/chrome/browser/ui/aura/accessibility/automation_manager_aura.cc
+++ b/chrome/browser/ui/aura/accessibility/automation_manager_aura.cc
@@ -132,6 +132,9 @@ void AutomationManagerAura::Reset(bool reset_serializer) {
 void AutomationManagerAura::SendEvent(BrowserContext* context,
                                       views::AXAuraObjWrapper* aura_obj,
                                       ui::AXEvent event_type) {
+  if (!current_tree_serializer_)
+    return;
+
   if (!context && g_browser_process->profile_manager()) {
     context = g_browser_process->profile_manager()->GetLastUsedProfile();
   }