Use ScopedTaskEnvironment instead of MessageLoopForUI in ViewsTestBase.

ui/views/test/views_test_base.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 "ui/views/test/views_test_base.h"
 
 #include <utility>
 
 #include "base/environment.h"
 #include "base/run_loop.h"
@@ skipping 30 matching lines @@
 
   return using_argb_visual;
 #else
   return false;
 #endif
 }
 
 }  // namespace
 
 ViewsTestBase::ViewsTestBase()
-    : setup_called_(false),
+    : scoped_task_environment_(
+          base::test::ScopedTaskEnvironment::MainThreadType::UI),
+      setup_called_(false),
       teardown_called_(false),
       has_compositing_manager_(InitializeVisuals()) {}
 
 ViewsTestBase::~ViewsTestBase() {
   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";
 }
 
@@ skipping 45 matching lines @@
 
 void ViewsTestBase::SimulateNativeDestroy(Widget* widget) {
   test_helper_->platform_test_helper()->SimulateNativeDestroy(widget);
 }
 
 gfx::NativeWindow ViewsTestBase::GetContext() {
   return test_helper_->GetContext();
 }
 
 }  // namespace views