Use constexpr TaskTraits constructor in net.

net/url_request/url_fetcher_impl_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 "net/url_request/url_fetcher_impl.h"
 
 #include <stdint.h>
 #include <string.h>
 
 #include <algorithm>
@@ skipping 506 matching lines @@
   std::string data;
   ASSERT_TRUE(delegate.fetcher()->GetResponseAsString(&data));
   EXPECT_EQ(kDefaultResponseBody, data);
 }
 
 // Create the fetcher from a sequenced (not single-threaded) task. Verify that
 // the expected response is received.
 TEST_F(URLFetcherTest, SequencedTaskTest) {
   base::test::ScopedTaskScheduler scoped_task_scheduler(
       base::MessageLoop::current());
-  auto sequenced_task_runner =
-      base::CreateSequencedTaskRunnerWithTraits(base::TaskTraits());
+  auto sequenced_task_runner = base::CreateSequencedTaskRunnerWithTraits({});
 
   auto delegate = base::MakeUnique<WaitingURLFetcherDelegate>();
   sequenced_task_runner->PostTask(
       FROM_HERE, base::Bind(&WaitingURLFetcherDelegate::CreateFetcher,
                             base::Unretained(delegate.get()),
                             test_server_->GetURL(kDefaultResponsePath),
                             URLFetcher::GET, CreateCrossThreadContextGetter()));
   base::RunLoop().RunUntilIdle();
   delegate->StartFetcherAndWait();
 
@@ skipping 1031 matching lines @@
   EXPECT_EQ(-1, delegate.fetcher()->GetResponseCode());
   EXPECT_FALSE(delegate.fetcher()->GetResponseHeaders());
   std::string data;
   EXPECT_TRUE(delegate.fetcher()->GetResponseAsString(&data));
   EXPECT_TRUE(data.empty());
 }
 
 }  // namespace
 
 }  // namespace net