Use constexpr TaskTraits constructor in chrome.

chrome/browser/printing/cloud_print/test/cloud_print_proxy_process_browsertest.cc

Index: chrome/browser/printing/cloud_print/test/cloud_print_proxy_process_browsertest.cc
diff --git a/chrome/browser/printing/cloud_print/test/cloud_print_proxy_process_browsertest.cc b/chrome/browser/printing/cloud_print/test/cloud_print_proxy_process_browsertest.cc
index 8fea42e6f2c7fd8f84c83ab6af0f467ec786f8ef..ff0d49be6506ed5d5616fc7e979102d4d72e6e89 100644
--- a/chrome/browser/printing/cloud_print/test/cloud_print_proxy_process_browsertest.cc
+++ b/chrome/browser/printing/cloud_print/test/cloud_print_proxy_process_browsertest.cc
@@ -483,9 +483,7 @@ void CloudPrintProxyPolicyStartupTest::WaitForConnect() {
 
   mojo::MessagePipe pipe;
   base::PostTaskWithTraits(
-      FROM_HERE,
-      base::TaskTraits().MayBlock().WithPriority(
-          base::TaskPriority::BACKGROUND),
+      FROM_HERE, {base::MayBlock(), base::TaskPriority::BACKGROUND},
       base::BindOnce(&ConnectAsync, base::Passed(&pipe.handle1),
                      GetServiceProcessChannel()));
   ServiceProcessControl::GetInstance()->SetChannel(