Use constexpr TaskTraits constructor in chrome.

chrome/browser/chromeos/file_manager/open_with_browser.cc

Index: chrome/browser/chromeos/file_manager/open_with_browser.cc
diff --git a/chrome/browser/chromeos/file_manager/open_with_browser.cc b/chrome/browser/chromeos/file_manager/open_with_browser.cc
index eb9352d7254cee39a458e767dc8f36af3139dc71..c7583fe796f6f2b26a212fb349b554a42455841b 100644
--- a/chrome/browser/chromeos/file_manager/open_with_browser.cc
+++ b/chrome/browser/chromeos/file_manager/open_with_browser.cc
@@ -170,7 +170,7 @@ bool OpenFileWithBrowser(Profile* profile,
       // The file is local (downloaded from an attachment or otherwise copied).
       // Parse the file to extract the Docs url and open this url.
       base::PostTaskWithTraitsAndReplyWithResult(
-          FROM_HERE, base::TaskTraits().MayBlock(),
+          FROM_HERE, {base::MayBlock()},
           base::Bind(&ReadUrlFromGDocAsync, file_path),
           base::Bind(&OpenNewTab, profile));
     }