Use constexpr TaskTraits constructor in chrome.

chrome/browser/android/webapk/webapk_installer.cc

 // Copyright 2016 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 "chrome/browser/android/webapk/webapk_installer.h"
 
 #include "base/android/build_info.h"
 #include "base/android/jni_android.h"
 #include "base/android/jni_string.h"
 #include "base/android/path_utils.h"
@@ skipping 162 matching lines @@
 // Calls the callback when the |webapk| request is created.
 void OnWebApkProtoBuilt(
     const base::Callback<void(std::unique_ptr<webapk::WebApk>)>& callback,
     std::unique_ptr<webapk::WebApk> webapk) {
   callback.Run(std::move(webapk));
 }
 
 // Returns task runner for running background tasks.
 scoped_refptr<base::TaskRunner> GetBackgroundTaskRunner() {
   return base::CreateTaskRunnerWithTraits(
-      base::TaskTraits()
-          .MayBlock()
-          .WithPriority(base::TaskPriority::BACKGROUND)
-          .WithShutdownBehavior(base::TaskShutdownBehavior::SKIP_ON_SHUTDOWN));
+      {base::MayBlock(), base::TaskPriority::BACKGROUND,
+       base::TaskShutdownBehavior::SKIP_ON_SHUTDOWN});
 }
 
 }  // anonymous namespace
 
 WebApkInstaller::~WebApkInstaller() {
   JNIEnv* env = base::android::AttachCurrentThread();
   Java_WebApkInstaller_destroy(env, java_ref_);
   java_ref_.Reset();
 }
 
@@ skipping 303 matching lines @@
       net::URLFetcher::Create(server_url, net::URLFetcher::POST, this);
   url_fetcher_->SetRequestContext(request_context_getter_);
   std::string serialized_request;
   request_proto->SerializeToString(&serialized_request);
   url_fetcher_->SetUploadData(kProtoMimeType, serialized_request);
   url_fetcher_->SetLoadFlags(
       net::LOAD_DISABLE_CACHE | net::LOAD_DO_NOT_SEND_COOKIES |
       net::LOAD_DO_NOT_SAVE_COOKIES | net::LOAD_DO_NOT_SEND_AUTH_DATA);
   url_fetcher_->Start();
 }