Use ScopedTaskEnvironment instead of MessageLoopForUI in chrome tests.

chrome/browser/ui/cocoa/toolbar/app_toolbar_button_cell_unittest.mm

 // Copyright (c) 2013 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.
 
 #import "chrome/browser/ui/cocoa/toolbar/app_toolbar_button_cell.h"
 
 #include "base/macros.h"
-#include "base/message_loop/message_loop.h"
+#include "base/test/scoped_task_environment.h"
 #import "chrome/browser/ui/cocoa/test/cocoa_test_helper.h"
 
 @interface TestAppToolbarButton : NSButton
 @end
 
 @implementation TestAppToolbarButton
 
 + (Class)cellClass {
   return [AppToolbarButtonCell class];
 }
 
 @end
 
 class AppToolbarButtonCellTest : public CocoaTest {
  protected:
-  AppToolbarButtonCellTest() {
+  AppToolbarButtonCellTest()
+      : scoped_task_environment_(
+            base::test::ScopedTaskEnvironment::MainThreadType::UI) {
     base::scoped_nsobject<NSButton> button([[TestAppToolbarButton alloc]
         initWithFrame:NSMakeRect(0, 0, 29, 29)]);
     button_ = button;
     [[test_window() contentView] addSubview:button_];
   }
 
   NSButton* button_;
   base::scoped_nsobject<AppToolbarButtonCell> cell_;
-  base::MessageLoopForUI message_loop_;  // Needed for gfx::Animation.
+  base::test::ScopedTaskEnvironment
+      scoped_task_environment_;  // Needed for gfx::Animation.

[sky, 2017/04/27 22:17:46]

Move the comment above the member.

[fdoray, 2017/05/01 17:44:59]

Done.

 
  private:
   DISALLOW_COPY_AND_ASSIGN(AppToolbarButtonCellTest);
 };
 
 TEST_VIEW(AppToolbarButtonCellTest, button_)