Use constexpr TaskTraits constructor in chrome.

chrome/browser/extensions/chrome_url_request_util.cc

Index: chrome/browser/extensions/chrome_url_request_util.cc
diff --git a/chrome/browser/extensions/chrome_url_request_util.cc b/chrome/browser/extensions/chrome_url_request_util.cc
index 033178c209bdab00998c7be89b82e58cdfa2aee5..f137be74bf6bba5dfbf708b13e61d29f04cb0723 100644
--- a/chrome/browser/extensions/chrome_url_request_util.cc
+++ b/chrome/browser/extensions/chrome_url_request_util.cc
@@ -70,7 +70,7 @@ class URLRequestResourceBundleJob : public net::URLRequestSimpleJob {
 
     std::string* read_mime_type = new std::string;
     base::PostTaskWithTraitsAndReplyWithResult(
-        FROM_HERE, base::TaskTraits().MayBlock(),
+        FROM_HERE, {base::MayBlock()},
         base::Bind(&net::GetMimeTypeFromFile, filename_,
                    base::Unretained(read_mime_type)),
         base::Bind(&URLRequestResourceBundleJob::OnMimeTypeRead,