Use constexpr TaskTraits constructor in extensions.

extensions/browser/api/file_handlers/mime_util.cc

 // Copyright 2013 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 "extensions/browser/api/file_handlers/mime_util.h"
 
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/task_scheduler/post_task.h"
 #include "base/threading/thread_task_runner_handle.h"
@@ skipping 56 matching lines @@
     callback.Run(mime_type);
     return;
   }
 
   // MIME type not available with metadata, hence try to guess it from the
   // file's extension.
   std::unique_ptr<std::string> mime_type_from_extension(new std::string);
   std::string* const mime_type_from_extension_ptr =
       mime_type_from_extension.get();
   base::PostTaskWithTraitsAndReply(
-      FROM_HERE, base::TaskTraits().MayBlock(),
+      FROM_HERE, {base::MayBlock()},
       base::Bind(base::IgnoreResult(&net::GetMimeTypeFromFile), local_path,
                  mime_type_from_extension_ptr),
       base::Bind(&OnGetMimeTypeFromFileForNonNativeLocalPathCompleted,
                  base::Passed(&mime_type_from_extension), callback));
 }
 #endif
 
 // Called when sniffing for MIME type in the native local file is completed.
 void OnSniffMimeTypeForNativeLocalPathCompleted(
     std::unique_ptr<std::string> mime_type,
@@ skipping 21 matching lines @@
     const base::Callback<void(const std::string&)>& callback) {
   if (!mime_type->empty()) {
     callback.Run(*mime_type);
     return;
   }
 
   std::unique_ptr<std::string> sniffed_mime_type(
       new std::string(kMimeTypeApplicationOctetStream));
   std::string* const sniffed_mime_type_ptr = sniffed_mime_type.get();
   base::PostTaskWithTraitsAndReply(
-      FROM_HERE, base::TaskTraits().MayBlock(),
+      FROM_HERE, {base::MayBlock()},
       base::Bind(&SniffMimeType, local_path, sniffed_mime_type_ptr),
       base::Bind(&OnSniffMimeTypeForNativeLocalPathCompleted,
                  base::Passed(&sniffed_mime_type), callback));
 }
 
 // Fetches MIME type for a local path and returns it with a |callback|.
 void GetMimeTypeForLocalPath(
     content::BrowserContext* context,
     const base::FilePath& local_path,
     const base::Callback<void(const std::string&)>& callback) {
@@ skipping 11 matching lines @@
     return;
   }
 #endif
 
   // For native local files, try to guess the mime from the extension. If
   // not available, then try to sniff if.
   std::unique_ptr<std::string> mime_type_from_extension(new std::string);
   std::string* const mime_type_from_extension_ptr =
       mime_type_from_extension.get();
   base::PostTaskWithTraitsAndReply(
-      FROM_HERE, base::TaskTraits().MayBlock(),
+      FROM_HERE, {base::MayBlock()},
       base::Bind(base::IgnoreResult(&net::GetMimeTypeFromFile), local_path,
                  mime_type_from_extension_ptr),
       base::Bind(&OnGetMimeTypeFromFileForNativeLocalPathCompleted, local_path,
                  base::Passed(&mime_type_from_extension), callback));
 }
 
 MimeTypeCollector::MimeTypeCollector(content::BrowserContext* context)
     : context_(context), left_(0), weak_ptr_factory_(this) {}
 
 MimeTypeCollector::~MimeTypeCollector() {}
@@ skipping 42 matching lines @@
         FROM_HERE, base::Bind(callback_, base::Passed(&result_)));
     // Release the callback to avoid a circullar reference in case an instance
     // of this class is a member of a ref counted class, which instance is bound
     // to this callback.
     callback_ = CompletionCallback();
   }
 }
 
 }  // namespace app_file_handler_util
 }  // namespace extensions