[Aura] Support always-on-top top level window.

ui/aura/test/aura_test_base.cc

 // Copyright (c) 2011 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 "ui/aura/test/aura_test_base.h"
 
 #if defined(OS_WIN)
 #include <ole2.h>
 #endif
 
@@ skipping 20 matching lines @@
 #if defined(OS_WIN)
   OleUninitialize();
 #endif
   CHECK(setup_called_)
       << "You have overridden SetUp but never called super class's SetUp";
   CHECK(teardown_called_)
       << "You have overridden TearDown but never called super class's TearDown";
 
   // Flush the message loop because we have pending release tasks
   // and these tasks if un-executed would upset Valgrind.
-  message_loop_.RunAllPendingWithDispatcher(
-      Desktop::GetInstance()->GetDispatcher());
+  RunAllPendingInMessageLoop();
 
   // Ensure that we don't use the previously-allocated static Desktop object
   // later -- on Linux, it holds a reference to our message loop's X connection.
   aura::Desktop::DeleteInstanceForTesting();
 }
 
 TestStackingClient* AuraTestBase::GetTestStackingClient() {
   return static_cast<TestStackingClient*>(
       aura::Desktop::GetInstance()->stacking_client());
 }
 
 void AuraTestBase::SetUp() {
   testing::Test::SetUp();
   setup_called_ = true;
 }
 
 void AuraTestBase::TearDown() {
   teardown_called_ = true;
   testing::Test::TearDown();
 }
 
+void AuraTestBase::RunAllPendingInMessageLoop() {
+  message_loop_.RunAllPendingWithDispatcher(
+      Desktop::GetInstance()->GetDispatcher());
+}
+
 }  // namespace test
 }  // namespace aura