Use constexpr TaskTraits constructor in base (part 2).

base/observer_list_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 "base/observer_list.h"
 #include "base/observer_list_threadsafe.h"
 
 #include <utility>
 #include <vector>
 
@@ skipping 582 matching lines @@
 
   WaitableEvent task_running(WaitableEvent::ResetPolicy::AUTOMATIC,
                              WaitableEvent::InitialState::NOT_SIGNALED);
   WaitableEvent barrier(WaitableEvent::ResetPolicy::AUTOMATIC,
                         WaitableEvent::InitialState::NOT_SIGNALED);
 
   // This must be after the declaration of |barrier| so that tasks posted to
   // TaskScheduler can safely use |barrier|.
   test::ScopedTaskEnvironment scoped_task_environment;
 
-  CreateSequencedTaskRunnerWithTraits(TaskTraits().WithBaseSyncPrimitives())
+  CreateSequencedTaskRunnerWithTraits({WithBaseSyncPrimitives()})
       ->PostTask(FROM_HERE,
                  base::Bind(&ObserverListThreadSafe<Foo>::AddObserver,
                             observer_list, Unretained(&observer)));
   TaskScheduler::GetInstance()->FlushForTesting();
 
   observer_list->Notify(FROM_HERE, &Foo::Observe, 1);
   observer.WaitForNotificationRunning();
   observer_list->RemoveObserver(&observer);
 
   observer.Unblock();
@@ skipping 434 matching lines @@
     // However, the first Observe() call will add a second observer: at this
     // point, it != observer_list.end() should be true, and Observe() should be
     // called on the newly added observer on the next iteration of the loop.
     observer.Observe(10);
   }
 
   EXPECT_EQ(-10, b.total);
 }
 
 }  // namespace base