Use constexpr TaskTraits constructor in chromecast.

chromecast/browser/url_request_context_factory.cc

Index: chromecast/browser/url_request_context_factory.cc
diff --git a/chromecast/browser/url_request_context_factory.cc b/chromecast/browser/url_request_context_factory.cc
index edcdfe9c41fc3b31064460d3b1542809e762f3dd..89e43f6ce8a37acf3487bde72e763d92f7600a49 100644
--- a/chromecast/browser/url_request_context_factory.cc
+++ b/chromecast/browser/url_request_context_factory.cc
@@ -288,11 +288,8 @@ void URLRequestContextFactory::InitializeMainContextDependencies(
         url::kFileScheme,
         base::MakeUnique<net::FileProtocolHandler>(
             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})));
     DCHECK(set_protocol);
   }