Re-enable some aura_shell_unittests for asan failure has been resolved in app list.

ash/system/tray/system_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/tray/system_tray.h"
 
 #include <vector>
 
 #include "ash/system/status_area_widget.h"
 #include "ash/system/tray/system_tray_item.h"
@@ skipping 146 matching lines @@
   // tray.
   test_item->tray_view()->SetVisible(false);
   EXPECT_EQ(widget_size.ToString(),
             tray->GetWidget()->GetWindowScreenBounds().size().ToString());
 
   test_item->tray_view()->SetVisible(true);
   EXPECT_EQ(new_size.ToString(),
             tray->GetWidget()->GetWindowScreenBounds().size().ToString());
 }
 
-// Disabled due to a use-after-free, see http://crbug.com/127539.
-TEST_F(SystemTrayTest, DISABLED_SystemTrayNotifications) {
+TEST_F(SystemTrayTest, SystemTrayNotifications) {
   scoped_ptr<SystemTray> tray(CreateSystemTray());
   ASSERT_TRUE(tray->GetWidget());
 
   TestItem* test_item = new TestItem;
   TestItem* detailed_item = new TestItem;
   tray->AddTrayItem(test_item);
   tray->AddTrayItem(detailed_item);
 
   // Ensure the tray views are created.
   ASSERT_TRUE(test_item->tray_view() != NULL);
@@ skipping 50 matching lines @@
   tray->ShowDefaultView(BUBBLE_USE_EXISTING);
   RunAllPendingInMessageLoop();
 
   EXPECT_EQ(bubble_bounds.ToString(), test_item->default_view()->GetWidget()->
       GetWindowScreenBounds().ToString());
   EXPECT_EQ(widget, test_item->default_view()->GetWidget());
 }
 
 }  // namespace test
 }  // namespace ash