Run FileSelectHelper::ProcessSelectedFilesMac in parallel in TaskScheduler.

chrome/browser/file_select_helper.cc

 // Copyright (c) 2012 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/file_select_helper.h"
 
 #include <stddef.h>
 
 #include <string>
 #include <utility>
 
 #include "base/bind.h"
 #include "base/files/file_enumerator.h"
 #include "base/files/file_util.h"
 #include "base/memory/ptr_util.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
+#include "base/task_scheduler/post_task.h"
 #include "build/build_config.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/platform_util.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/profiles/profile_manager.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_list.h"
 #include "chrome/browser/ui/chrome_select_file_policy.h"
 #include "chrome/grit/generated_resources.h"
 #include "content/public/browser/browser_thread.h"
@@ skipping 163 matching lines @@
   if (dialog_type_ == ui::SelectFileDialog::SELECT_UPLOAD_FOLDER) {
     StartNewEnumeration(path, kFileSelectEnumerationId,
                         render_frame_host_->GetRenderViewHost());
     return;
   }
 
   std::vector<ui::SelectedFileInfo> files;
   files.push_back(file);
 
 #if defined(OS_MACOSX)
-  content::BrowserThread::PostTask(
-      content::BrowserThread::FILE_USER_BLOCKING,
-      FROM_HERE,
+  base::PostTaskWithTraits(
+      FROM_HERE, base::TaskTraits().MayBlock().WithShutdownBehavior(
+                     base::TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN),
       base::Bind(&FileSelectHelper::ProcessSelectedFilesMac, this, files));
 #else
   NotifyRenderFrameHostAndEnd(files);
 #endif  // defined(OS_MACOSX)
 }
 
 void FileSelectHelper::MultiFilesSelected(
     const std::vector<base::FilePath>& files,
     void* params) {
   std::vector<ui::SelectedFileInfo> selected_files =
       FilePathListToSelectedFileInfoList(files);
 
   MultiFilesSelectedWithExtraInfo(selected_files, params);
 }
 
 void FileSelectHelper::MultiFilesSelectedWithExtraInfo(
     const std::vector<ui::SelectedFileInfo>& files,
     void* params) {
   if (!files.empty() && IsValidProfile(profile_)) {
     base::FilePath path = files[0].file_path;
     if (dialog_mode_ != FileChooserParams::UploadFolder)
       path = path.DirName();
     profile_->set_last_selected_directory(path);
   }
 #if defined(OS_MACOSX)
-  content::BrowserThread::PostTask(
-      content::BrowserThread::FILE_USER_BLOCKING,
-      FROM_HERE,
+  base::PostTaskWithTraits(
+      FROM_HERE, base::TaskTraits().MayBlock().WithShutdownBehavior(
+                     base::TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN),
       base::Bind(&FileSelectHelper::ProcessSelectedFilesMac, this, files));
 #else
   NotifyRenderFrameHostAndEnd(files);
 #endif  // defined(OS_MACOSX)
 }
 
 void FileSelectHelper::FileSelectionCanceled(void* params) {
   NotifyRenderFrameHostAndEnd(std::vector<ui::SelectedFileInfo>());
 }
 
@@ skipping 449 matching lines @@
 
 // static
 base::FilePath FileSelectHelper::GetSanitizedFileName(
     const base::FilePath& suggested_filename) {
   if (suggested_filename.empty())
     return base::FilePath();
   return net::GenerateFileName(
       GURL(), std::string(), std::string(), suggested_filename.AsUTF8Unsafe(),
       std::string(), l10n_util::GetStringUTF8(IDS_DEFAULT_DOWNLOAD_FILENAME));
 }