Fix popup crash on ChromeOS.

ash/system/web_notification/web_notification_tray_unittest.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/system/web_notification/web_notification_tray.h"
 
 #include <vector>
 
 #include "ash/display/display_manager.h"
 #include "ash/root_window_controller.h"
@@ skipping 190 matching lines @@
   UpdateNotification("test_id2", "test_id3");
   EXPECT_TRUE(GetTray()->IsPopupVisible());
 
   // Removing the first notification should not hide the popup bubble.
   RemoveNotification("test_id1");
   EXPECT_TRUE(GetTray()->IsPopupVisible());
 
   // Removing the visible notification should hide the popup bubble.
   RemoveNotification("test_id3");
   EXPECT_FALSE(GetTray()->IsPopupVisible());
+
+  // Now test that we can show multiple popups and then show the message center.
+  AddNotification("test_id4");
+  AddNotification("test_id5");
+  EXPECT_TRUE(GetTray()->IsPopupVisible());
+
+  GetTray()->message_center_tray_->ShowMessageCenterBubble();
+  GetTray()->message_center_tray_->HideMessageCenterBubble();
+
+  EXPECT_FALSE(GetTray()->IsPopupVisible());
 }
 
 using message_center::NotificationList;
 
 
 // Flakily fails. http://crbug.com/229791
 TEST_F(WebNotificationTrayTest, DISABLED_ManyMessageCenterNotifications) {
   // Add the max visible notifications +1, ensure the correct visible number.
   size_t notifications_to_add =
       message_center::kMaxVisibleMessageCenterNotifications + 1;
@@ skipping 247 matching lines @@
 
   // System tray is created on the primary display. The popups in the secondary
   // tray aren't affected.
   GetSystemTray()->ShowDefaultView(BUBBLE_CREATE_NEW);
   EXPECT_GT(work_area.size().GetArea(), GetPopupWorkArea().size().GetArea());
   EXPECT_EQ(work_area_second.ToString(),
             GetPopupWorkAreaForTray(GetSecondaryTray()).ToString());
 }
 
 }  // namespace ash