Reland of "file_manager: Migrate FILE thread to TaskScheduler"

chrome/browser/chromeos/file_manager/file_browser_handlers.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/chromeos/file_manager/file_browser_handlers.h"
 
 #include <stddef.h>
 #include <algorithm>
 #include <set>
 #include <utility>
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/files/file_util.h"
 #include "base/i18n/case_conversion.h"
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/strings/utf_string_conversions.h"
+#include "base/task_scheduler/post_task.h"
 #include "chrome/browser/chromeos/drive/file_system_util.h"
 #include "chrome/browser/chromeos/file_manager/app_id.h"
 #include "chrome/browser/chromeos/file_manager/fileapi_util.h"
 #include "chrome/browser/chromeos/file_manager/open_with_browser.h"
 #include "chrome/browser/chromeos/fileapi/file_system_backend.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/browser_finder.h"
 #include "chrome/common/extensions/api/file_browser_handlers/file_browser_handler.h"
 #include "chrome/common/extensions/api/file_manager_private.h"
@@ skipping 182 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(FileBrowserHandlerExecutor);
 };
 
 // static
 std::unique_ptr<FileDefinitionList>
 FileBrowserHandlerExecutor::SetupFileAccessPermissions(
     scoped_refptr<storage::FileSystemContext> file_system_context_handler,
     const scoped_refptr<const Extension>& handler_extension,
     const std::vector<FileSystemURL>& file_urls) {
-  DCHECK_CURRENTLY_ON(BrowserThread::FILE);
   DCHECK(handler_extension.get());
 
   storage::ExternalFileSystemBackend* backend =
       file_system_context_handler->external_backend();
 
   std::unique_ptr<FileDefinitionList> file_definition_list(
       new FileDefinitionList);
   for (size_t i = 0; i < file_urls.size(); ++i) {
     const FileSystemURL& url = file_urls[i];
 
@@ skipping 51 matching lines @@
     const std::vector<FileSystemURL>& file_urls,
     const file_tasks::FileTaskFinishedCallback& done) {
   done_ = done;
 
   // Get file system context for the extension to which onExecute event will be
   // sent. The file access permissions will be granted to the extension in the
   // file system context for the files in |file_urls|.
   scoped_refptr<storage::FileSystemContext> file_system_context(
       util::GetFileSystemContextForExtensionId(profile_, extension_->id()));
 
-  BrowserThread::PostTaskAndReplyWithResult(
-      BrowserThread::FILE,
-      FROM_HERE,
-      base::Bind(&SetupFileAccessPermissions,
-                 file_system_context,
-                 extension_,
+  base::PostTaskWithTraitsAndReplyWithResult(
+      FROM_HERE, {base::MayBlock(), base::TaskPriority::USER_BLOCKING},
+      base::Bind(&SetupFileAccessPermissions, file_system_context, extension_,
                  file_urls),
       base::Bind(&FileBrowserHandlerExecutor::ExecuteAfterSetupFileAccess,
                  weak_ptr_factory_.GetWeakPtr()));
 }
 
 void FileBrowserHandlerExecutor::ExecuteAfterSetupFileAccess(
     std::unique_ptr<FileDefinitionList> file_definition_list) {
   // Outlives the conversion process, since bound to the callback.
   const FileDefinitionList& file_definition_list_ref =
       *file_definition_list.get();
@@ skipping 218 matching lines @@
       if (common_handlers.empty())
         return FileBrowserHandlerList();
     }
   }
 
   return common_handlers;
 }
 
 }  // namespace file_browser_handlers
 }  // namespace file_manager