Use constexpr TaskTraits constructor in chrome.

chrome/browser/mac/keystone_glue.mm

Index: chrome/browser/mac/keystone_glue.mm
diff --git a/chrome/browser/mac/keystone_glue.mm b/chrome/browser/mac/keystone_glue.mm
index 14046162eb695495c7ffb128fb0168d55de84505..87fb51c8f721fbf78cc763f2c4465da0ac3ea7a8 100644
--- a/chrome/browser/mac/keystone_glue.mm
+++ b/chrome/browser/mac/keystone_glue.mm
@@ -71,13 +71,10 @@ class PerformBridge : public base::RefCountedThreadSafe<PerformBridge> {
     DCHECK(sel);
 
     scoped_refptr<PerformBridge> op = new PerformBridge(target, sel, arg);
-    base::PostTaskWithTraits(
-        FROM_HERE, base::TaskTraits()
-                       .MayBlock()
-                       .WithPriority(base::TaskPriority::BACKGROUND)
-                       .WithShutdownBehavior(
-                           base::TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN),
-        base::Bind(&PerformBridge::Run, op.get()));
+    base::PostTaskWithTraits(FROM_HERE,
+                             {base::MayBlock(), base::TaskPriority::BACKGROUND,
+                              base::TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN},
+                             base::Bind(&PerformBridge::Run, op.get()));
   }
 
   // Convenience for the no-argument case.