Remove MessageLoop::current()->task_runner() in ui.

ui/base/test/windowed_nsnotification_observer.mm

 // Copyright 2015 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 "ui/base/test/windowed_nsnotification_observer.h"
 
 #import <Cocoa/Cocoa.h>
 
+#include "base/location.h"
 #include "base/run_loop.h"
+#include "base/single_thread_task_runner.h"
 #include "base/test/test_timeouts.h"
+#include "base/threading/thread_task_runner_handle.h"
 
 @interface WindowedNSNotificationObserver ()
 - (void)onNotification:(NSNotification*)notification;
 @end
 
 @implementation WindowedNSNotificationObserver
 
 @synthesize notificationCount = notificationCount_;
 
 - (id)initForNotification:(NSString*)name {
@@ skipping 41 matching lines @@
 
   ++notificationCount_;
   if (runLoop_)
     runLoop_->Quit();
 }
 
 - (BOOL)waitForCount:(int)minimumCount {
   while (notificationCount_ < minimumCount) {
     const int oldCount = notificationCount_;
     base::RunLoop runLoop;
-    base::MessageLoop::current()->task_runner()->PostDelayedTask(
+    base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
         FROM_HERE, runLoop.QuitClosure(), TestTimeouts::action_timeout());
     runLoop_ = &runLoop;
     runLoop.Run();
     runLoop_ = nullptr;
 
     // If there was no new notification, it must have been a timeout.
     if (notificationCount_ == oldCount)
       break;
   }
   return notificationCount_ >= minimumCount;
 }
 
 - (BOOL)wait {
   return [self waitForCount:1];
 }
 
 @end