Use constexpr TaskTraits constructor in chrome.

chrome/browser/extensions/chrome_url_request_util.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/extensions/chrome_url_request_util.h"
 
 #include <string>
 
 #include "base/files/file_path.h"
 #include "base/memory/weak_ptr.h"
@@ skipping 52 matching lines @@
     const ResourceBundle& rb = ResourceBundle::GetSharedInstance();
     *data = rb.LoadDataResourceBytes(resource_id_);
 
     // Add the Content-Length header now that we know the resource length.
     response_info_.headers->AddHeader(
         base::StringPrintf("%s: %s", net::HttpRequestHeaders::kContentLength,
                            base::SizeTToString((*data)->size()).c_str()));
 
     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,
                    weak_factory_.GetWeakPtr(), mime_type, charset, *data,
                    base::Owned(read_mime_type), callback));
 
     return net::ERR_IO_PENDING;
   }
 
   void GetResponseInfo(net::HttpResponseInfo* info) override {
@@ skipping 92 matching lines @@
                                              resource_id,
                                              content_security_policy,
                                              send_cors_header);
     }
   }
   return NULL;
 }
 
 }  // namespace chrome_url_request_util
 }  // namespace extensions