ash: Do not use MessageLoopForUI when not needed.

ash/wm/workspace/workspace_event_handler_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/wm/workspace/workspace_event_handler.h"
 
 #include "ash/screen_util.h"
 #include "ash/shell.h"
 #include "ash/test/ash_test_base.h"
 #include "ash/wm/window_state.h"
 #include "ash/wm/window_util.h"
 #include "ash/wm/wm_event.h"
 #include "ash/wm/workspace_controller.h"
 #include "ash/wm/workspace_controller_test_helper.h"
+#include "base/thread_task_runner_handle.h"
 #include "ui/aura/client/aura_constants.h"
 #include "ui/aura/test/test_window_delegate.h"
 #include "ui/aura/window.h"
 #include "ui/aura/window_tree_host.h"
 #include "ui/base/hit_test.h"
 #include "ui/events/event_processor.h"
 #include "ui/events/event_utils.h"
 #include "ui/events/test/event_generator.h"
 #include "ui/gfx/screen.h"
 #include "ui/wm/core/window_util.h"
@@ skipping 421 matching lines @@
 }
 
 // Verifies deleting the window while in a run loop doesn't crash.
 TEST_F(WorkspaceEventHandlerTest, DeleteWhileInRunLoop) {
   aura::test::TestWindowDelegate delegate;
   const gfx::Rect bounds(10, 20, 30, 40);
   scoped_ptr<aura::Window> window(CreateTestWindow(&delegate, bounds));
   delegate.set_window_component(HTCAPTION);
 
   ASSERT_TRUE(aura::client::GetWindowMoveClient(window->GetRootWindow()));
-  base::MessageLoop::current()->DeleteSoon(FROM_HERE, window.get());
+  base::ThreadTaskRunnerHandle::Get()->DeleteSoon(FROM_HERE, window.get());
   aura::client::GetWindowMoveClient(window->GetRootWindow())
       ->RunMoveLoop(window.release(),
                     gfx::Vector2d(),
                     aura::client::WINDOW_MOVE_SOURCE_MOUSE);
 }
 
 // Verifies that double clicking in the header does not maximize if the target
 // component has changed.
 TEST_F(WorkspaceEventHandlerTest,
     DoubleClickTwoDifferentTargetsDoesntMaximize) {
@@ skipping 76 matching lines @@
   delegate.set_window_component(HTCAPTION);
   generator.PressRightButton();
   generator.ReleaseRightButton();
   EXPECT_FALSE(window_state->IsMaximized());
   ClickButtonWithFlags(&generator, ui::EF_LEFT_MOUSE_BUTTON,
                        ui::EF_IS_DOUBLE_CLICK);
   EXPECT_FALSE(window_state->IsMaximized());
 }
 
 }  // namespace ash