cros: do not try to activate system tray bubble if it is in process of closing

ash/common/system/tray/system_tray.cc

Index: ash/common/system/tray/system_tray.cc
diff --git a/ash/common/system/tray/system_tray.cc b/ash/common/system/tray/system_tray.cc
index 463e6fecdb7025529ba95e2c3854ad5c79a7543d..b8e731699a88b026570b6308a64a0e46efb31c73 100644
--- a/ash/common/system/tray/system_tray.cc
+++ b/ash/common/system/tray/system_tray.cc
@@ -698,6 +698,10 @@ void SystemTray::CreateKeyEventWatcher() {
 
 void SystemTray::ActivateBubble() {
   TrayBubbleView* bubble_view = GetSystemBubble()->bubble_view();
+  // If system tray bubble is in the process of closing, do not try to activate
+  // bubble.
+  if (bubble_view->GetWidget()->IsClosed())
+    return;
   bubble_view->set_can_activate(true);
   bubble_view->GetWidget()->Activate();
 }